Adjectives that start with the letter “O” offer a rich vocabulary to describe various aspects of people, places, things, and experiences. These adjectives can range from expressing emotions and physical characteristics to describing sizes, shapes, and qualities. Let’s explore a comprehensive list of 100 adjectives beginning with “O,” each followed by a simple, one-word meaning to help understand and use them effectively in our daily conversations and writing.
Adjectives That Start With O
- One-Quarter
- Ommatidial
- Outbound
- Overcharged
- Ordained
- Omotic
- Occlusal
- Out-Of-Body
- Orological
- Oxlike
- Opalescent
- Overraced
- Orthologous
- Open-Armed
- Orcish
- Oafish
- Onetime
- Oxyntic
- Ovenproof
- Oniric
- Outlandish
- Occultural
- Orthognathic
- Octoid
- Occulent
- Oblite
- Onshore
- Obstreperous
- Omnipresent
- Obstetrick
- Oversparred
- Overcoated
- Out-Of-Date
- Onward
- Opposing
- Over-Assertive
- Overachiever
- Oriented
- Oofy
- Oozy
- Out-And-Out
- Originative
- One-Hour
- Overdressed
- Overinvolved
- Oversized
- Overcast
- Orangey
- Overmodest
- Obstetrical
- Oligotrophic
- Oronasal
- Oversmoothed
- Observant
- Overmighty
- Overalert
- Opposed
- Overdelicate
- Overextended
- Orderable
- Overstated
- One-Track
- On-Road
- Oysterless
- Outcast
- Orosensory
- Obvious
- Obsoleter
- Overfragrant
- Ordered
- Outdacious
- Oligosynaptic
- Ontological
- Overenthusiastic
- Overrash
- Over-Ripe
- Overapt
- Ocreate
- Outdate
- Outback
- Outflowing
- Osculating
- Occultic
- Ophiolitic
- Octal
- Overspecific
- Overread
- Obtuse-Angled
- Oppressed
- Opiate
- Oral
- Oversolicitous
- Overmuscled
- Operant
- Overriding
- One-Third
- On-Going
- Out Of Work
- Overexcitable
- Octoic
- Overforested
- Open-Hearted
- Oversolar
- Occlusive
- Overconscious
- Occultistic
- Overlayered
- Overfussy
- Ochre
- Overactive
- Optimific
- Out-Of-Context
- Orbiculate
- Olympic
- Ossicular
- Overneat
- Overreactive
- Obsolete
- Overslow
- Outcoming
- Obliterable
- Oversteered
- Outgunned
- Occidental
- On
- Ovation
- One-Fourth
- Overlying
- Orange
- On-The-Spot
- Open-Ended
- One-Half
- One-Armed
- Overattentive
- Overaged
- Ocellar
- Orthometric
- Outer
- Overanxious
- Optimum
- Occupied
- Overconscientious
- Overfocused
- Outfitted
- Osteogenic
- Operative
- Obeisaunt
- Oxygenic
- Onlest
- Outrageous
- Obsessed
- Outjutting
- Oystery
- Ozone-Friendly
- Occluded
- Overrank
- Ordurous
- Overconcerned
- Overfreighted
- Obsequious
- Operationalist
- Olivary
- Optothermal
- Overtroubled
- Operable
- Out-Of-Service
- Originless
- Obscene
- Oligosaline
- Orbitual
- Over-The-Top
- Overpriced
- Optospintronic
- Overfond
- Out-Of-Town
- Ossiferous
- Oscitant
- One-Note
- Oblique
- Overseas
- Orinasal
- Olympian
- Overmotivated
- Oxonian
- Ophidian
- Overlarge
- Omnidirectional
- Overreaching
- One-Ninth
- Osteoid
- Originable
- Overexerting
- Optative
- Onrushing
- Overfriezed
- Otherwise
- Ossom
- Oversimplistic
- Overdosed
- Omphalic
- Omissible
- Overweight
- Ox-Eyed
- Onirocritic
- Otterlike
- Overplayful
- Osseous
- Oneiric
- Oversuspicious
- Octacore
- Overfraught
- Object-Oriented
- Oblivious
- Objectless
- Oceanward
- Octogynous
- Out-Of-Court
- Omissive
- Ovulational
- Overladen
- Optimal
- Onanistic
- Over-Rated
- Overcommitted
- Occupational
- Overawed
- Oval
- Orkish
- Organizational
- Overconfident
- Orwellian
- Oblong
- Obstetricious
- Omophagous
- One-Shot
- One-To-One
- Otic
- Omani
- Ornamental
- Orienting
- Oncogenic
- Opened
- Over-The-Counter
- Octagonal
- Overbreathed
- Occasional
- Obscure
- Overabundant
- Overcritical
- Oxidized
- Overexposed
- Overgreedy
- Omohyoidean
- Obstinant
- Opportunistic
- Opthalmic
- Obstetric
- Orphaned
- Outland
- Oppositive
- Obliterated
- Oversoft
- Oaken
- Overdone
- Ovid
- Open-Eyed
- Overdocumented
- Opprobrious
- Overclose
- Oversewn
- Onlooking
- Organic
- Oversea
- Overfamiliar
- Overspeeding
- Overserious
- Obverse
- Opacular
- Oysterlike
- Originary
- Overfurnished
- Overhand
- Object-Based
- Overkeen
- Overclaimed
- Overhanded
- Once-Removed
- Opuntiaceous
- Oppositional
- Original
- Orient
- Opensightly
- Otter
- One-Way
- Outmost
- Owing
- One-Touch
- One-Seventh
- Oligosemic
- Obliquid
- Overfatigued
- Operating
- Open-Hearth
- Open-Book
- Osteoporotic
- Opinionated
- Outstanding
- Orbicular
- Over Sized
- Obviating
- Orographical
- Observing
- Overinformed
- Overcurious
- Outgoing
- Obsolescent
- Overcooked
- Omphalinoid
- Ostensive
- Outdated
- Operculated
- Overfrequent
- Octangular
- Overburdened
- Overfree
- Ornithogenic
- Occultive
- Obstruent
- Origenian
- Onymous
- Ochreous
- Os-Specific
- Octabasic
- Overcluttered
- Osteoarthritic
- Overexerted
- Osculatory
- Obliging
- Open-Handed
- Origenist
- Outbred
- Oversize
- Overland
- Out-Of-Order
- Oracular
- Open-Plan
- Other-Worldly
- Orthogenic
- Outraged
- Overturnable
- Oncoming
- Oregonian
- Opaline
- Overblown
- Osteal
- Orthopedic
- Overproud
- One-Eyed
- Obligatory
- Orientational
- Optokinetic
- Orthodontic
- Overworked
- Overnice
- Overdominant
- Orbless
- Overindulgent
- Oblationary
- Objectual
- Onkus
- Overturned
- Only
- Organismic
- Over
- Overlookable
- Orthotopic
- Operose
- Overforward
- Overracked
- Objectional
- Overflowing
- On-Off
- Orthodox
- Overdeveloped
- Opacifiable
- Over-Elaborate
- Oliguric
- Ownerless
- One-Day
- Ovate
- Opposite
- Over-Polite
- Overall
- Overdetermined
- Overclear
- Ominous
- Ornithological
- Orientated
- Oxalic
- Ochrous
- Overfulfilled
- Oversocialized
- One-Sided
- On-Stage
- One-Time
- Oratorial
- Overeager
- Onionless
- Overfed
- Opulent
- Overful
- Ocellated
- Omakase
- Obstacle-Ridden
- Obstructed
- Osmolar
- Orchestral
- Overwhelmed
- Oscillatory
- Obstinate
- Onygenaceous
- Opsonic
- On-Hand
- Onside
- Objective
- Overish
- Obsessive
- Outlined
- Optimistic
- Outcut
- Orthoepic
- Onesided
- Overbusy
- Overgenerous
- Organismal
- Occulomotor
- Orogastric
- Obdurant
- Outflung
- Orolabial
- Orthorhombic
- One-On-One
- Olive
- Orthograde
- Open-Air
- Over-Sensitive
- Overindebted
- Overvaliant
- Oblimin
- Oak
- Obligate
- Omasal
- Orolingual
- Oversnowed
- Owned
- Outlaw
- Opportune
- Omosternal
- Overachieving
- Overhasty
- Overbearing
- Ossified
- Octacosanoic
- Oncogenomic
- Optional
- Ornery
- Overcounted
- Out-Of-Pocket
- Overclothed
- Out-Of-State
- Orientating
- Obtuse
- Observable
- Orchestrated
- Openable
- Orgiastic
- Openhanded
- Ordinary
- Octogenarian
- Open-And-Shut
- Overhead
- Overstrung
- Overag
- Ovarian
- Overcoatless
- Out-Of-Print
- Ornithophilous
- Outward
- Outside
- Owlish
- Overconsiderate
- On-Air
- Oromucosal
- Overfriendly
- On-Camera
- Overemphatic
- Operatic
- Ordinate
- Oncological
- Oligotrichous
- Overdamped
- Overcoming
- Overwater
- Overweening
- Overtired
- Oblike
- Ovular
- Over-Fond
- Opephoroid
- Out-Of-Character
- Open-Mouthed
- Opacous
- Oscillating
- One-Off
- Overdramatic
- Overjoyed
- Obedient
- Octameric
- Overdoped
- Optic
- Overcrowded
- Ostrich-Like
- Obliterative
- Outspread
- Oven-Proof
- Obstructive
- Ontogenetic
- Obliged
- Opencast
- Opacating
- Orangy
- Overjittery
- Outsize
- Oyster
- Oxytocic
- On-Campus
- Obnoxious
- Obligational
- Optronic
- Overmuch
- Outlying
- Overdependent
- Oversophisticated
- Overrefined
- Overfull
- Occurrent
- Omnivorous
- Overhyped
- Overexcited
- Outmoded
- Outspoken
- Opposable
- Ossiculate
- Overtrusting
- Open-Minded
- On-Line
- Otoscopic
- Obstacular
- Overdue
- Overstuffed
- Overfucked
- Overcivilized
- Octolateral
- Outshore
- Omophagic
- Oviform
- Observational
- On-The-Job
- Optomotor
- Otterless
- Over-Zealous
- Oo
- Onomastic
- Opportunist
- Out-Of-Work
- Ontologic
- Omnipotent
- Overjubilant
- Origenistic
- Osmotic
- Omnibus
- Oroqen
- Orbital
- Outdoorsy
- Optical
- Orotund
- Oratorian
- Overcareful
- Overemotional
- Onerous
- Occluse
- Overcomplicated
- Overshot
- Overstimulated
- Operculate
- Overcoached
- Optotypic
- Oceanic
- Opaque
- One-Stop
- Overclad
- Occupiable
- Olivelike
- One-Piece
- Octahedral
- One-Legged
- Overnew
- Overtouristed
- Outclassed
- Overalled
- One-Tenth
- Orectic
- Oscine
- Orbitary
- Overloaded
- Oxblood
- Oncogenetic
- Outsized
- Overjoyous
- Orographic
- Obligated
- Overprotective
- Omphacine
- Occipital
- Overpowering
- Overintense
- On-Site
- Overuniform
- Octacyclic
- Orthogenetic
- Outboard
- Osteogenetic
- Objectionable
- Overbooked
- Onionlike
- Obscurant
- Oxyacetic
- Orangish
- Overbanked
- One-Eighth
- Overwhelming
- Oriental
- Obtrusive
- Onomatopoeic
- Obfuscatory
- Overt
- Ordinal
- Orgulous
- Overnighter
- Oob
- Obsignatory
- Overnight
- Orthogonal
- Ototoxic
- Oppressional
- One
- Osmobiotic
- Our
- Observed
- Osteopathic
- One-Gallused
- Orderly
- Oversubscribed
- Orosirian
- Opencut
- Octanoic
- Orblike
- Os
- Overproof
- Orogenital
- Opponent
- Ovigerous
- Overionized
- Occlusional
- Overjust
- Organized
- Overage
- Overpessimistic
- Opensource
- Overaggressive
- Onioned
- One-Handed
- Overforceful
- One-Fifth
- Overarm
- Outdoor
- Out
- Overready
- Orgasmic
- Ouvrierist
- Obedible
- Outright
- Oblate
- Obedt
- Obese
- Overoptimistic
- Obituary
- Ovaloid
- Overcautious
- Overgrown
- Opening
- Overlooked
- Onyx
- Overambitious
- Ostentatious
- Ocean-Going
- Overwrought
- Oversexed
- Other
- Ontic
- Overjealous
- Oysterish
- Obeisant
- Orinocan
- Omphacitic
- On-Scene
- Obsessional
- Overqualified
- Oversensitive
- Ower
- One-Sixth
- Osmometric
- Overly
- Oolitic
- Orogenic
- Ornate
- Oppilative
- Ostial
- Oppressive
- Operational
- Overmastering
- Obediential
- Outlawed
- Omniscient
- Over-Educated
- Ostensible
- Open-Faced
- Ordeal
- Oratorical
- Orphic
- Opercular
- Own
- Oviparous
- Overtight
- Overinclusive
- Occult
- Outermost
- Overheated
- One-Pot
- Optoelectronic
- Oniony
- Open
- Overbold
- Overfruitful
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(A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z)
Adjectives Starting With O
- Obedient – Compliant
- Objective – Unbiased
- Obliging – Helpful
- Oblique – Slanted
- Observant – Watchful
- Obsolete – Outdated
- Obstinate – Stubborn
- Obtrusive – Intrusive
- Obvious – Clear
- Occasional – Infrequent
- Occluded – Blocked
- Odd – Strange
- Odious – Hateful
- Odoriferous – Smelly
- Offbeat – Unusual
- Offensive – Insulting
- Offhand – Casual
- Official – Formal
- Oily – Greasy
- Ominous – Foreboding
- Omnipotent – All-powerful
- Omniscient – All-knowing
- Onerous – Burdensome
- Opaque – Non-transparent
- Open – Uncovered
- Open-minded – Accepting
- Operational – Functional
- Opinionated – Biased
- Opportune – Timely
- Opposite – Contrary
- Optimal – Best
- Optimistic – Hopeful
- Optional – Elective
- Opulent – Luxurious
- Oral – Spoken
- Orderly – Organized
- Ordinary – Common
- Organic – Natural
- Organized – Structured
- Oriented – Directed
- Original – Novel
- Ornamental – Decorative
- Orthodox – Conventional
- Oscillating – Swinging
- Outgoing – Sociable
- Outlandish – Bizarre
- Outrageous – Shocking
- Outspoken – Frank
- Outstanding – Exceptional
- Oval – Egg-shaped
- Overbearing – Dominating
- Overconfident – Cocky
- Overjoyed – Elated
- Overwhelmed – Overpowered
- Overt – Open
- Overweight – Heavy
- Overwrought – Agitated
- Oxidized – Rusty
- Oblivious – Unaware
- Occult – Mysterious
- Oceanic – Marine
- Octogenarian – Eighty-something
- Ocular – Visual
- Odius – Repugnant
- Officious – Meddlesome
- Ogle – Stare
- Oily – Unctuous
- Omnivorous – Eating everything
- Onerous – Taxing
- Opaque – Cloudy
- Operatic – Dramatic
- Opulent – Rich
- Oracular – Prophetic
- Ornate – Fancy
- Ossified – Hardened
- Ostentatious – Showy
- Ostracized – Excluded
- Otiose – Useless
- Outmoded – Old-fashioned
- Overcast – Cloudy
- Overdone – Exaggerated
- Overlooked – Missed
- Oversized – Large
- Overtly – Obviously
- Oxymoronic – Contradictory
- Oblong – Elongated
- Obscure – Vague
- Obstetric – Birth-related
- Oceanographic – Sea-studying
- Oligarchic – Ruled by few
- Omnipresent – Everywhere
- Oneiric – Dreamlike
- Operose – Laborious
- Opprobrious – Disgraceful
- Oratorical – Speaking well
- Ornithological – Bird-studying
- Ossify – Become bone
- Ostensible – Seeming
- Outrageous – Excessive
- Overt – Obvious
- Oxidative – Rust-causing
- Obligate – Bind
- Omissible – Skippable
- Onerous – Heavy
- Ophthalmic – Eye-related
- Optative – Wishing
- Oracular – Prophetic
- Ornery – Stubborn
- Ostentatious – Showy
- Outlandish – Bizarre
- Overarching – Encompassing
- Overzealous – Too enthusiastic
- Oxidizable – Rustable
Positive Adjectives That Start With O
- Open-hearted
- Opportune
- Optimistic
- Orderly
- Original
- Outgoing
- Outstanding
- Obedient
- Obliging
- Observant
- Open-minded
- Opportunistic
- Opulent
- Organized
- Ornate
- Overjoyed
- Overachieving
- Overflowing
- Overt
- Owlish
- Ownerless
- Ongoing
- Official
- Operative
- Opportunistic
- Overcoming
- Outperforming
- Overarching
- Outspread
- Ornamental
- Observable
- Outspoken
- Overjoyed
- Ovational
- Optimizable
- Outreaching
- Oxytocin-rich
- Obediently
- Overtly
- Olfactory-pleasing
- Ocean-loving
- Open-field
- Outsize
- Optimal
- Outlandish (in a good way)
- Out-of-the-box
- Oscillatory
- Objective
- Omnificent
- Omnipresent
Negative Adjectives That Start With O
- Obnoxious
- Obstinate
- Obsolete
- Ominous
- Overbearing
- Overcritical
- Overzealous
- Offhand
- Overwhelmed
- Oversensitive
- Odious
- Offputting
- Overconfident
- Overindulgent
- Overused
- Overambitious
- Overcautious
- Overdependent
- Overemotional
- Overpowering
- Overpriced
- Overrated
- Overreactive
- Overshadowed
- Oversized
- Overstated
- Overworked
- Overwrought
- Oafish
- Obdurate
- Oblivious
- Obscene
- Obsessive
- Obstructive
- Obtuse
- Occult
- Oily
- Onerous
- Opaque
- Oppressive
- Ornery
- Outdated
- Outrageous
- Overdone
- Overdrawn
- Overwound
- Overaggressive
- Overcritical
- Overhasty
- Overinflated
Adjectives Starting With Letter O To Describe A Person
- Open-minded – Willing to consider new ideas.
- Optimistic – Hopeful and confident about the future.
- Orderly – Neat and organized.
- Original – Creative and unique.
- Outgoing – Sociable and friendly.
- Outstanding – Exceptionally good.
- Obedient – Compliant and respectful to authority.
- Obliging – Ready to help others.
- Observant – Quick to notice things.
- Opportunistic – Good at taking advantage of opportunities.
- Organized – Able to plan things carefully and keep things tidy.
- Ornate – Elaborately or highly decorated.
- Overt – Open and not hidden.
- Owlish – Wise or resembling an owl in appearance.
- Objective – Not influenced by personal feelings or opinions.
- Operative – Effective and significant.
- Opulent – Wealthy or luxurious.
- Overachieving – Doing better than is expected.
- Overflowing – Abundant or plentiful.
- Olympian – Majestic; godlike.
- Onward – Moving forward or progressing.
- Opalescent – Shimmering with colors like an opal.
- Opinionated – Holding strong beliefs or judgments.
- Overcoming – Successful in dealing with difficulties.
- Overjoyed – Extremely happy.
- Olympic – Related to or resembling the Olympics, suggesting excellence.
- Optimal – Best or most favorable.
- Oratorical – Skilled in public speaking.
- Overzealous – Excessively enthusiastic.
- Oxygenated – Full of energy and vitality.
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