82 words starting with O

• object noun

  a thing you can see and touch; the aim of an activity

  There was a strange object on the table.

  Like thing, item, article

• objection noun

  a statement or feeling of disagreement

  Nobody raised an objection to having the class picnic on Friday.

  Like protest, complaint

• objective noun

  something you plan to achieve

  Our objective is to plant one hundred trees this year.

  Like goal, aim, target

• obligation noun

  something you must do because of a rule, promise, or duty

  Parents have an obligation to make sure their children go to school.

  Like duty, responsibility

• obscure adjective

  not well known; hard to understand or see clearly

  The book mentions an obscure village high in the hills.

  Like unknown, little-known, unclear

• observation noun

  the act of watching something carefully to learn about it

  Careful observation of the moon showed us how its shape changes each night.

• observe verb

  to watch something carefully to learn about it

  We observed the moon every night for a month and drew its shape.

  Like watch, study, notice

• observer noun

  a person who watches something carefully

  An observer at the top of the tower counted the passing birds.

  Like watcher, viewer, onlooker

• obtain verb

  to get something, especially by effort

  You can obtain a library card by filling in this form.

  Like get, acquire, gain

• obvious adjective

  easy to see or understand

  The answer was obvious once she drew a picture.

  Like clear, plain, evident

• obviously adverb

  in a way that anyone can see or understand; of course

  She was obviously tired after the long walk.

  Like clearly, plainly

• occasion noun

  a particular time when something happens; a special event

  My grandmother wears her best sari only on special occasions.

  Like event, time

• occasionally adverb

  sometimes, but not often

  We occasionally eat at a restaurant on special days.

  Like sometimes, now and then

• occupation noun

  a person’s job; the act of taking control of a place

  Please write your parents’ occupations on the form.

  Like job, profession, career

• occupy verb

  to fill or use a space or time; to take control of a place

  The big table occupies most of the room.

  Like fill, take up

• occur verb

  to happen, especially without being planned

  Earthquakes often occur in this part of the Himalaya.

  Like happen, take place

• occurrence noun

  something that happens; how often something happens

  Snow in Kathmandu is a rare occurrence, so children rush outside when it falls.

  Like event, incident, happening

• ocean noun

  a very large area of salt water covering much of the Earth

  The Pacific is the largest ocean in the world.

  Like sea

• odd adjective

  strange or unusual; describing a number that cannot be divided by two exactly

  Three, five and seven are odd numbers.

  Like strange, unusual

• offense noun

  a crime or act that breaks a rule; a feeling of being upset by rudeness

  Riding a motorbike without a helmet is an offense.

  Like crime

• offer verb

  to ask if someone would like something; to say you are willing to do something

  Our neighbor offered us a cup of tea when we visited.

  Like propose

• office noun

  a room or building where people work at desks

  The principal’s office is next to the library.

  Like workplace

• officer noun

  a person with authority in the army or police; a person with an official job

  The police officer helped the children cross the road.

  Like official

• official adjective

  approved by a government or someone in charge

  Nepali is the official language of Nepal.

  Like formal, authorized

• offspring noun

  the young of a person, animal or plant

  A cat can have several offspring in one litter.

  Like young, children

• often adverb

  many times; frequently

  It often rains in the afternoon during the monsoon.

  Like frequently, regularly

• oil noun

  a thick liquid used for cooking, or for fuel and machines

  Heat the oil in the pan before you add the vegetables.

• old adjective

  having lived or existed for many years; not new

  The old temple in the square was built hundreds of years ago.

  Like aged, ancient, elderly

• once adverb

  one time only; at some time in the past

  I have visited Lumbini only once, when I was eight.

  Like formerly

• online adjective

  connected to or available on the internet

  We had online classes at home when heavy rain closed the school for a week.

• only adverb

  no more than; and nobody or nothing else

  Only three students finished the long race before the bell rang.

  Like just, merely, solely

• onset noun

  the beginning of something, especially something unpleasant

  Farmers try to finish the harvest before the onset of winter.

  Like start, beginning

• onwards adverb

  forward from a particular time or place

  The museum is open from ten o’clock onwards.

  Like forward

• open verb

  to move something so that it is no longer closed

  Please open the window and let some fresh air in.

• opera noun

  a play in which the words are sung to music

  The opera told the story with beautiful singing.

• operate verb

  to make a machine work; to cut open a body to repair it

  Only trained workers may operate this machine.

  Like run, use, work

• operation noun

  cutting into someone’s body to repair it; the way something works

  My grandfather had an operation on his knee.

  Like surgery

• operator noun

  a person who controls a machine; a company that runs a service

  The crane operator lifted the steel beams carefully.

• opinion noun

  what you think or believe about something

  In my opinion, mangoes are the best fruit.

  Like view, belief

• opponent noun

  a person or team you play or compete against

  She shook hands with her opponent after the chess match.

  Like rival, competitor

• opportunity noun

  a good chance to do something

  The trip gave us an opportunity to see the rhinos in Chitwan.

  Like chance, opening

• oppose verb

  to disagree with something and try to stop it

  Many villagers opposed the plan to cut down the forest.

  Like resist, object to, fight

• opposite adjective

  completely different; on the other side facing something

  Hot and cold are opposite words, and so are up and down.

  Like reverse, contrary

• opposition noun

  strong disagreement with a plan; the team or person you play against

  There was opposition to the plan to cut down the old trees.

  Like resistance, disagreement

• optical adjective

  relating to sight or to light

  A microscope is an optical instrument that makes small things look bigger.

  Like visual

• optimal adjective

  the best or most effective possible

  The optimal time to plant rice is at the start of the monsoon.

  Like best, ideal

• optimum adjective

  best or most suitable for a particular purpose

  Seeds sprout fastest at an optimum temperature of about twenty-five degrees.

  Like best, ideal

• option noun

  something you can choose

  We had two options: take the bus or walk.

  Like choice, alternative

• oral adjective

  spoken rather than written; relating to the mouth

  We have an oral exam in English next week.

  Like spoken, verbal

• orange noun

  a round, sweet citrus fruit with a thick reddish-yellow skin

  I peeled an orange and shared it with my sister.

• order noun

  the way things are arranged one after another; an instruction to do something

  Put the words on your list in alphabetical order, starting with the letter A.

  Like sequence, arrangement, command

• ordinary adjective

  normal and usual, not special

  It was an ordinary school day until the snow began to fall.

  Like normal, usual, common

• organ noun

  a part of the body with a particular job, such as the heart or lungs

  The skin is the largest organ of the human body.

• organic adjective

  grown without chemical fertilizers or pesticides; relating to living things

  My aunt grows organic vegetables on her rooftop.

  Like natural

• organism noun

  a single living thing, such as a plant, animal or bacterium

  A drop of pond water can contain thousands of tiny organisms.

  Like living thing

• organization noun

  a group of people working together for a shared purpose

  The Red Cross is an organization that helps people in emergencies.

  Like group, association

• organize verb

  to plan and arrange something carefully

  Our class organized a cleaning day at the river.

  Like arrange, plan

• orient verb

  to find your position or direction; to aim something toward a particular direction

  We used the mountains to orient ourselves on the map.

  Like position, direct, align

• orientation noun

  the direction something faces or is placed in; an introduction to a new place or activity

  New students attend an orientation on the first day of school.

  Like direction, position

• origin noun

  the point or place where something begins

  The origin of the Bagmati River is in the hills north of Kathmandu.

  Like source, beginning

• original adjective

  existing at the beginning; new and not copied

  The original plan was to go on Monday, but we changed it.

  Like first, initial

• originally adverb

  at first, before something changed

  The building was originally a palace, but now it is a museum.

  Like initially, at first

• oscillation noun

  a regular movement backward and forward

  The oscillation of a pendulum is used to keep time in old clocks.

  Like swing, vibration

• otherwise adverb

  if not; or else

  Hurry up, otherwise we will miss the bus.

  Like or else

• outcome noun

  the result of an action or event

  We waited for the outcome of the science competition.

  Like result, consequence

• outer adjective

  on the outside or farther from the center

  The outer layer of an onion is dry and brown.

  Like outside, external, exterior

• outlet noun

  a way out for water, gas or feelings; a socket in a wall for electricity

  Sports are a good outlet for extra energy.

  Like exit, vent

• outline noun

  a line showing the outer shape of something; a short plan of the main points

  First, draw the outline of the map, then color the districts.

  Like sketch

• output noun

  the amount something produces; information a computer gives out

  The factory’s output doubled after it bought new machines.

  Like production

• outside noun

  the outer part or side of something

  The outside of the coconut is hard and hairy.

  Like exterior, surface

• overall adjective

  including everything; when everything is considered

  The overall cost of the trip was less than we expected.

  Like total, general, whole

• overcome verb

  to succeed in dealing with a problem or difficulty

  She overcame her fear of water and learned to swim.

  Like defeat, conquer, beat

• overhead adverb

  above your head; in the sky

  A flock of geese flew overhead on their way south.

  Like above, aloft

• overlap verb

  to cover part of something by lying over it; to share some parts with something else

  The roof tiles overlap so that rain runs off.

  Like overlie

• overseas adverb

  in or to a foreign country across the sea

  My aunt works overseas and visits us during Dashain.

  Like abroad

• overview noun

  a short general description of a subject, without the details

  The teacher gave us an overview of the topics in this term.

  Like summary, outline

• owe verb

  to need to pay back money that you borrowed

  I owe my friend fifty rupees for the snacks.

• own verb

  to have something that belongs to you as your property

  My uncle owns a small tea shop near the bus park in Pokhara.

  Like possess, have

• owner noun

  a person something belongs to

  The owner of the lost dog put up signs around the town.

  Like possessor, holder

• ownership noun

  the fact of owning something

  The ownership of the land passed from father to son.

  Like possession

• oxidize verb

  to change chemically by combining with oxygen, as when iron rusts

  Iron oxidizes when it is left out in wet weather.

• oxygen noun

  a gas with no color or smell that people, animals and plants need to live

  Climbers on Everest often carry extra oxygen because the air there is so thin.