112 Adjectives That Start With O
O is a small letter with a heavy accent. Its best-known words are almost all complaints — obnoxious, officious, obstinate, overbearing, ostentatious — and the handful of compliments it offers tend to be quiet ones: obliging, observant, orderly. This page lists 112 adjectives that start with O, grouped by the job each does, with a plain meaning beside every word.
Many of its over- words describe a thing done to excess rather than a thing done badly, and that distinction is worth holding on to — though not every O-word starting with those letters belongs to the prefix at all. Overt comes from Old French for open, and overcast uses over- in the sense of covering.
All 112 adjectives at a glance
Every word on this page in one block. Each is defined further down.
obliging, observant, open, open-handed, open-minded, opportune, optimal, optimistic, opulent, orderly, organised, original, outgoing, outstanding, obedient, objective, overjoyed, obdurate, obnoxious, obscene, obsequious, obsessive, obstinate, obstructive, obtuse, odious, offensive, officious, oily, one-sided, onerous, opinionated, opportunistic, oppressive, ostentatious, outlandish, outrageous, overbearing, overrated, overwrought, ornery, odorous, occupied, offhand, old, omnivorous, only, oppressed, orthodox, outspoken, overworked, oblivious, obliged, outdoorsy, overqualified, overprotective, overwhelmed, oval, orange, opaque, oversized, obese, olive, ochre, opalescent, ornate, outsized, owlish, oblong, oblique, obsessional, offbeat, old-fashioned, open-hearted, overcautious, overconfident, overzealous, oracular, obstreperous, outré, obligatory, obsolete, obvious, occasional, overcast, occult, oceanic, odd, official, ornamental, organic, omniscient, olden, ominous, ongoing, operatic, optional, oral, orbital, ordinary, otiose, outdoor, outward, ostensible, otherworldly, outdated, outlying, outbound, overdue, overcrowded, overt, overwhelming
Positive
Praise-side words. Obliging and obedient look similar and are not: obliging chooses to help, obedient is doing as told.
| Adjective | What it means |
|---|---|
| obliging | willing to do a favour without being pressed |
| observant | quick to notice what others miss |
| open | hiding nothing and inviting approach |
| open-handed | giving without counting the cost |
| open-minded | willing to hear a case against your own view |
| opportune | arriving at exactly the right moment |
| optimal | the best available under the constraints |
| optimistic | expecting things to turn out well |
| opulent | lavishly rich and comfortable |
| orderly | arranged so anyone could find anything |
| organised | keeping work and time under control |
| original | not derived from anything before it |
| outgoing | at ease starting a conversation with a stranger |
| outstanding | clearly above everything around it |
| obedient | doing as instructed |
| objective | judging without letting feeling in |
| overjoyed | filled with more delight than can be hidden |
Negative
One of the letter’s two largest sections. Note how many describe a failure of proportion rather than of character — overbearing, overwrought, ostentatious and opportunistic all name someone doing a reasonable thing too hard.
| Adjective | What it means |
|---|---|
| obdurate | unmoved by pity or persuasion |
| obnoxious | unpleasant enough to drive people away |
| obscene | grossly indecent, especially about sex or violence |
| obsequious | fawning in order to please a superior |
| obsessive | unable to let a thought go |
| obstinate | holding a position past the point of reason |
| obstructive | getting in the way on purpose |
| obtuse | slow to grasp what is plain to others |
| odious | deserving hatred |
| offensive | causing hurt or anger |
| officious | exercising small authority with relish |
| oily | smoothly insincere |
| one-sided | weighted unfairly toward one party |
| onerous | imposing a heavy burden |
| opinionated | stating views more readily than hearing them |
| opportunistic | taking advantage without scruple |
| oppressive | weighing down those beneath it |
| ostentatious | showing wealth to be seen doing it |
| outlandish | strange enough to draw stares |
| outrageous | shocking beyond what can be excused |
| overbearing | imposing your will on everyone present |
| overrated | valued more highly than it deserves |
| overwrought | strained past composure |
| ornery | bad-tempered and awkward for its own sake |
| odorous | carrying a smell, usually an unwelcome one |
To describe a person
A mix of circumstance and disposition. Only here means having no siblings, which is the one sense of the word that behaves as a describing word for people.
| Adjective | What it means |
|---|---|
| occupied | busy with something and not free |
| offhand | casual in a way that can read as dismissive |
| old | far along in years |
| omnivorous | eating everything, or reading everything |
| only | having no brothers or sisters |
| oppressed | held down by those with power |
| orthodox | holding to established belief |
| outspoken | saying what you think regardless of the room |
| overworked | given more to do than the hours allow |
| oblivious | unaware of what is happening around you |
| obliged | grateful for a service done |
| outdoorsy | happiest in the open air |
| overqualified | holding more credentials than the post requires |
| overprotective | shielding someone past what they need |
| overwhelmed | carrying more than can be managed |
Physical appearance
O gives more shape and colour words than most letters its size. Opalescent and ochre both name a colour by naming a material.
| Adjective | What it means |
|---|---|
| oval | shaped like an elongated circle |
| orange | the colour between red and yellow |
| opaque | letting no light pass |
| oversized | larger than the usual measure |
| obese | carrying dangerous excess weight |
| olive | yellowish green, or of that skin tone |
| ochre | earthy yellow-brown |
| opalescent | showing shifting milky colours |
| ornate | covered in elaborate decoration |
| outsized | unusually large; exaggerated in size |
| owlish | round-eyed and solemn behind glasses |
| oblong | elongated in one direction; in British use, a rectangle longer than it is wide |
| oblique | set at a slant |
Personality
Settled disposition. Three of these carry the over- prefix, and each names a virtue that has run past its useful point.
| Adjective | What it means |
|---|---|
| obsessional | fixed on one preoccupation in the clinical sense |
| offbeat | unconventional in a likeable way |
| old-fashioned | not modern; belonging to a past era |
| open-hearted | showing feeling without guarding it |
| overcautious | too cautious |
| overconfident | surer than the evidence allows |
| overzealous | pursuing a cause past what it warrants |
| oracular | speaking as if from hidden knowledge |
| obstreperous | noisily resistant to control |
| outré | unconventional to the point of impropriety |
Everyday and descriptive
Objects, times and conditions.
| Adjective | What it means |
|---|---|
| obligatory | required, with no option to decline |
| obsolete | no longer produced or usable at all |
| obvious | needing no explanation |
| occasional | happening now and then |
| overcast | covered by unbroken cloud |
| occult | hidden from ordinary understanding |
| oceanic | of the open sea |
| odd | strange, or not divisible by two |
| official | carrying the authority of an office |
| ornamental | added for beauty rather than use |
| organic | grown rather than assembled |
| omniscient | knowing everything there is to know |
| olden | belonging to a distant past |
| ominous | warning that something bad is coming |
| ongoing | still in progress |
| operatic | grand and heightened in manner |
| optional | left to choice |
| oral | spoken rather than written |
| orbital | moving in a curved path around something |
| ordinary | of the common kind |
| otiose | serving no purpose, of a remark or a task |
| outdoor | taking place outside |
| outward | on the outside, or going away from a place |
| ostensible | stated as the reason, though not the real one |
| otherworldly | seeming to belong somewhere other than here |
| outdated | behind current practice, though still working |
| outlying | far from the centre |
| outbound | heading away from a place, on the outward leg |
| overdue | later than the time set |
| overcrowded | holding more than the space allows |
| overt | done openly, with nothing concealed |
| overwhelming | too great in force to withstand |
Using them in a sentence
A list is only half the job. These show the words carrying weight rather than sitting decoratively in front of a noun.
- He was obliging to strangers and obstinate with anyone who had known him a while.
- The hall was ornate, overcrowded and thoroughly oppressive.
- An ostensible apology, delivered in an offhand tone.
- The sky went overcast, then ominous, and the light turned ochre.
- Her reading was omnivorous and her memory for it obsessive.
O-words people mix up
| Pair | The difference that matters |
|---|---|
| obtuse / obstinate | Obtuse is a failure to understand. Obstinate is a refusal to move. One is about ability, the other about will. |
| officious / official | Official means carrying real authority. Officious means volunteering help nobody asked for, usually with a little authority to enjoy. |
| oblivious / obvious | They share only the ob- prefix and are easily mistyped for one another. Oblivious is unaware; obvious is unmissable. |
| opaque / obscure | Opaque blocks light or sense entirely. Obscure is merely hard to find or hard to follow. |
| ostensible / ostentatious | Ostensible means claimed rather than true. Ostentatious means done to be seen. They share a root and almost nothing else. |
Related guides
- Adjectives for the ocean — where oceanic, opaque and overcast do their closest work.
- Adjectives for objects — expands the shape and material words above.
- Adjectives for an office — for orderly, official and officious.
- Adjectives for opinions — pairs with opinionated, objective and orthodox.
- Adjectives for objectives — for optimal, obligatory and optional.
- Adjectives for an octopus — a closer look at oceanic description.
Checked against Merriam-Webster, the Chicago Manual of Style and the AP Stylebook. Spotted an error? Tell us — see our editorial policy.
