Meaning: Welcoming and accessible; allowing communication.

Part of speech: adjective

Example: The manager has an open-door policy.

Category: Business

Synonyms:

• accessible
• welcoming

Antonyms:

• closed
• exclusive

Meaning: Not having a clear or definite limit.

Part of speech: adjective

Example: The discussion was open-ended, allowing for many ideas.

Category: General

Synonyms:

• indefinite
• unrestricted

Antonyms:

• definite
• restricted

Meaning: Referring to clothing with a wide or open neckline.

Part of speech: adjective

Example: He wore an open-necked shirt to the party.

Category: Fashion

Synonyms: collarless

Meaning: Referring to a design with few or no walls separating spaces.

Part of speech: adjective

Example: They have an open-plan office to encourage collaboration.

Category: Architecture

Synonyms: open concept

Antonyms: closed-off

Meaning: Referring to a vehicle without a roof.

Part of speech: adjective

Example: They rented an open-top car for their trip.

Category: Transportation

Synonyms: convertible

Meaning: A dramatic work set to music, typically in a theatrical setting.

Part of speech: noun

Example: They went to see an opera at the grand theater.

Category: Arts › Music

Synonyms: musical drama

Meaning: A theater building specifically designed for opera performances.

Part of speech: noun

Example: The opera house was beautifully designed.

Category: Arts › Theatre

Synonyms: theater

Meaning: A room in a hospital where surgeries are performed.

Part of speech: noun

Example: The patient was taken to the operating room.

Category: Medicine

Synonyms: surgery room

Meaning: Software that manages computer hardware and software resources.

Part of speech: noun

Example: Windows is a popular operating system.

Category: Technology

Synonyms: OS

Meaning: A table on which surgical operations are performed.

Part of speech: noun

Example: The surgeon prepared the operating table for the procedure.

Category: Medicine

Synonyms: surgery table

Meaning: A room where surgical operations are performed, often with an audience.

Part of speech: noun

Example: The medical students observed the surgery in the operating theatre.

Category: Medicine

Synonyms: surgery room

Meaning: Ready for use or functioning.

Part of speech: adjective

Example: The new equipment is now operational.

Category: Technology

Synonyms:

• functional
• working

Antonyms:

• non-operational
• inoperative

Meaning: A person who operates equipment or machinery.

Part of speech: noun

Example: The operator controlled the crane during the construction.

Category: Technology

Synonyms:

• machinist
• controller

Meaning: A medical doctor specializing in eye and vision care.

Part of speech: noun

Example: She visited the ophthalmologist for her eye exam.

Category: Medicine › Ophthalmology

Synonyms: eye doctor

Meaning: A survey of public opinion on a specific issue.

Part of speech: noun

Example: The opinion poll showed a shift in voter preferences.

Category: Politics

Synonyms:

• survey
• poll

Meaning: Having strong opinions that are often not based on reason.

Part of speech: adjective

Example: He is very opinionated about politics.

Category: Communication

Synonyms:

• biased
• dogmatic

Antonyms:

• open-minded
• neutral

Meaning: A nocturnal marsupial native to the Americas.

Part of speech: noun

Example: The opossum is known for playing dead when threatened.

Category: Nature › Wildlife

Synonyms: marsupial

Meaning: In disagreement with something.

Part of speech: adjective

Example: She was opposed to the proposed changes.

Category: Politics

Synonyms:

• against
• contrary

Antonyms:

• supportive
• agreeing

Meaning: In conflict or disagreement with something.

Part of speech: adjective

Example: The opposing teams played fiercely.

Category: Politics

Synonyms:

• contradictory
• antagonistic

Antonyms:

• supportive
• cooperative

Meaning: Resistance or dissent, expressed in action or argument.

Part of speech: noun

Example: There was strong opposition to the new policy.

Category: Politics

Synonyms:

• resistance
• dissent

Antonyms:

• support
• agreement

Meaning: To choose to participate in something.

Part of speech: verb

Example: You can opt in to receive newsletters.

Category: Decision Making

Synonyms:

• subscribe
• enroll

Antonyms: opt out

Meaning: To choose not to participate in something.

Part of speech: verb

Example: You can opt out of receiving promotional emails.

Category: Decision Making

Synonyms:

• decline
• withdraw

Antonyms: opt in

Meaning: Relating to sight or the eye.

Part of speech: adjective

Example: The optical illusion tricked my eyes.

Category: Science › Ophthalmology

Synonyms:

• visual
• ocular

Meaning: A thin fiber that transmits light signals for communication.

Part of speech: noun

Example: Optical fibre is used in high-speed internet connections.

Category: Technology › Telecommunications

Synonyms: fiber optic

Meaning: A professional who designs and fits eyeglasses and contact lenses.

Part of speech: noun

Example: She visited the optician for a new pair of glasses.

Category: Medicine › Ophthalmology

Synonyms: eye care professional

Meaning: A hopeful attitude about the future.

Part of speech: noun

Example: Her optimism helped the team stay motivated.

Category: Personal Development

Synonyms:

• hopefulness
• positivity

Antonyms:

• pessimism
• negativity

Meaning: To make something as effective or functional as possible.

Part of speech: verb

Example: They aim to optimize the production process.

Category: Technology

Synonyms:

• enhance
• improve

Antonyms:

• deteriorate
• worsen

Meaning: To choose not to participate in something.

Part of speech: verb

Example: You can opt-out of the newsletter if you wish.

Category: Business › Marketing

Synonyms:

• withdraw
• exclude

Antonyms: opt-in

Meaning: Having a color similar to that of an orange.

Part of speech: adjective

Example: She painted the walls a bright orangey hue.

Category: Arts › Color

Synonyms: orange-colored

Meaning: A large ape with long arms and reddish-brown hair, found in the rainforests of Borneo and Sumatra.

Part of speech: noun

Example: The orang-utan is known for its intelligence.

Category: Nature › Animals

Synonyms: ape

Meaning: A spherical object or shape.

Part of speech: noun

Example: The globe is an orb representing the Earth.

Category: Science › Geometry

Synonyms:

• sphere
• ball

Meaning: A large group of musicians playing together, typically including strings, woodwinds, brass, and percussion.

Part of speech: noun

Example: The orchestra performed a beautiful symphony.

Category: Arts › Music

Synonyms:

• band
• ensemble

Meaning: A diverse family of flowering plants known for their beautiful blooms.

Part of speech: noun

Example: She received an orchid as a gift.

Category: Nature › Plants

Synonyms: flower

Meaning: A painful or difficult experience.

Part of speech: noun

Example: The hike was an ordeal, but we made it to the top.

Category: Life › Challenges

Synonyms:

• trial
• test

Antonyms:

• comfort
• ease

Meaning: To give orders to someone in a bossy manner.

Part of speech: verb

Example: He tends to order around his younger siblings.

Category: Life › Relationships

Synonyms:

• command
• dictate

Meaning: A number that indicates position or order in a sequence.

Part of speech: noun

Example: First, second, and third are examples of ordinal numbers.

Category: Mathematics › Numbers

Synonyms: position number

Meaning: A naturally occurring solid material from which a metal or valuable mineral can be extracted.

Part of speech: noun

Example: Iron ore is mined for steel production.

Category: Science › Geology

Synonyms:

• mineral
• rock

Meaning: A musical instrument with pipes that produces sound by air passing through them.

Part of speech: noun

Example: The organ in the church is very old.

Category: Arts › Music

Synonyms: instrument

Meaning: Relating to or derived from living matter; also refers to food produced without synthetic chemicals.

Part of speech: adjective

Example: I prefer to buy organic vegetables.

Category: Food › Agriculture

Synonyms:

• natural
• biological

Antonyms: synthetic

Meaning: A group of people organized for a particular purpose.

Part of speech: noun

Example: The charity is a non-profit organisation.

Category: Business › Non-Profit

Synonyms:

• group
• association