List of Vocabulary Words that start with the letter “O” and their definitions.
- Obdurate – stubborn or unyielding; resistant to persuasion or change
- Obsequious – overly attentive or submissive to authority
- Obviate – to prevent or make unnecessary
- Occlude – to block or obstruct
- Occult – relating to supernatural or supernatural phenomena; hidden or secret
- Ocular – relating to the eye or vision
- Odious – extremely unpleasant or repugnant
- Odometer – an instrument for measuring the distance traveled by a vehicle
- Odorous – having a strong or distinctive smell, often unpleasant
- Offal – the internal organs or entrails of an animal, especially when used as food
- Offhand – casual or carefree; done without prior thought or preparation
- Olfactory – relating to the sense of smell
- Olive – a small, oval-shaped fruit with a smooth, yellow-green skin and a single seed, often used for oil or as a food
- Omen – a sign or warning of a future event, especially a portentous or ominous one
- Omnipotent – all-powerful; having unlimited or infinite power
- Omniscient – having complete or unlimited knowledge
- Onomatopoeia – the formation of a word, as cuckoo, meow, honk, or boom, by imitation of a sound made by or associated with its referent
- Opacity – the quality or state of being obscure or difficult to see through
- Opaque – not transparent or translucent; difficult to see through
- Opine – to express a personal opinion or belief
- Opprobrium – strong disapproval or criticism, often accompanied by public shame or disgrace
- Optometry – the branch of healthcare that deals with the examination and correction of visual defects through the use of eyeglasses or contact lenses
- Opulent – wealthy or luxurious in an ostentatious or showy way
- Orator – a public speaker, especially one who is eloquent or skilled
- Oratory – the art of effective public speaking
- Orb – a sphere or ball-shaped object
- Orchard – a piece of land planted with fruit trees
- Oriface – an opening, especially one that leads into a hollow space or tube in a body
- Ormolu – an alloy of copper, zinc, and sometimes tin, used to make decorative objects, such as frames or clocks
- Orphic – mysterious or obscure in a way that is difficult to understand
- Orthodontics – the branch of dentistry that deals with the correction of teeth and jaws that are misaligned or positioned improperly
- Orthogonal – perpendicular; intersecting at a right angle
- Osmosis – the movement of a solvent, such as water, through a membrane or porous barrier, from a less concentrated solution to a more concentrated one, equalizing the concentrations on both sides
- Ostracize – to exclude from a group or society, especially by general consent
- Outlandish – strange or bizarre; not typical or conventional
- Outmaneuver – to outsmart or outwit through clever planning or strategy
- Outmoded – no longer fashionable or relevant; outdated
- Outpost – a small settlement or military base located in a remote or isolated area
- Outrage – an extreme or violent reaction of anger or indignation
- Outré – unconventional or unusual in a way that is striking
