Meaning: Happening in a short time; fast.

Part of speech: adjective

Example: The rapid growth of technology is impressive.

Category: Science

Synonyms:

• quick
• swift

Antonyms:

• slow
• leisurely

Meaning: Thin or less dense; often used to describe a select group.

Part of speech: adjective

Example: The rarefied atmosphere at high altitudes can be challenging.

Category: Science

Synonyms:

• thin
• exclusive

Antonyms:

• dense
• common

Meaning: A narrow beam of light or energy.

Part of speech: noun

Example: A ray of sunlight broke through the clouds.

Category: Science › Physics

Synonyms:

• beam
• light

Meaning: To respond to something.

Part of speech: verb

Example: He didn't react to the news as expected.

Category: Science › Chemistry

Synonyms:

• respond
• reply

Meaning: A response to something.

Part of speech: noun

Example: Her reaction to the news was surprising.

Category: Science › Chemistry

Synonyms:

• response
• reply

Antonyms:

• indifference
• apathy

Meaning: Responding to a stimulus or change.

Part of speech: adjective

Example: Reactive strategies are often used in crisis management.

Category: Science › Chemistry

Synonyms:

• responsive
• adaptive

Antonyms:

• inactive
• unresponsive

Meaning: A device or vessel in which nuclear reactions occur.

Part of speech: noun

Example: The reactor was designed to produce energy efficiently.

Category: Science › Nuclear Physics

Synonyms:

• nuclear reactor
• vessel

Meaning: A substance used in a chemical reaction to detect or measure another substance.

Part of speech: noun

Example: The chemist added a reagent to the solution to test for impurities.

Category: Science › Chemistry

Synonyms:

• chemical
• substance

Meaning: An object or space used to contain something.

Part of speech: noun

Example: The receptacle was filled with water.

Category: Science › Physics

Synonyms:

• container
• holder

Meaning: To restore something to its original state or form.

Part of speech: verb

Example: You can reconstitute the dried soup by adding water.

Category: Science › Chemistry

Synonyms:

• restore
• rebuild

Meaning: Extremely hot or heated.

Part of speech: adjective

Example: The red-hot metal was ready to be shaped.

Category: Science › Physics

Synonyms:

• scorching
• burning

Antonyms: cold

Meaning: To make something smaller or less in amount.

Part of speech: verb

Example: We need to reduce our energy consumption.

Category: Science › Mathematics

Synonyms:

• decrease
• diminish

Antonyms: increase

Meaning: The act of entering again, especially into a place or situation.

Part of speech: noun

Example: The re-entry of the spacecraft was successful.

Category: Science › Aerospace

Synonyms:

• return
• reaccess

Meaning: To throw back light or heat; to think deeply.

Part of speech: verb

Example: The mirror will reflect the light beautifully.

Category: Science › Physics

Synonyms:

• mirror
• ponder

Meaning: The image seen in a mirror or on a surface; careful thought.

Part of speech: noun

Example: Her reflection in the water was clear and beautiful.

Category: Science › Physics

Synonyms:

• image
• thought

Meaning: An object that reflects light.

Part of speech: noun

Example: The reflector on the bicycle helps increase visibility at night.

Category: Science › Physics

Synonyms:

• mirror
• reflective surface

Meaning: To change the direction of light as it passes through a medium.

Part of speech: verb

Example: The glass prism will refract the sunlight into a rainbow.

Category: Science › Optics

Synonyms:

• bend
• deflect

Meaning: To grow again or restore something.

Part of speech: verb

Example: The lizard can regenerate its tail.

Category: Science

Synonyms:

• renew
• revive

Antonyms:

• destroy
• diminish

Meaning: The theory that space and time are relative and not absolute.

Part of speech: noun

Example: Einstein's theory of relativity changed our understanding of physics.

Category: Science › Physics

Synonyms: relationality

Meaning: the acquisition of information about an object from a distance

Part of speech: noun

Example: Remote sensing is used in environmental monitoring.

Category: Science › Geography

Synonyms:

• aerial sensing
• distant observation

Meaning: a substance used to remove something

Part of speech: noun

Example: She used a paint remover to clean the surface.

Category: Science

Synonyms:

• cleaner
• solvent

Meaning: able to be replaced or restored

Part of speech: adjective

Example: Solar energy is a renewable resource.

Category: Science › Energy

Synonyms:

• sustainable
• regenerative

Meaning: to drive away or force back

Part of speech: verb

Example: The spray is designed to repel insects.

Category: Science

Synonyms:

• drive away
• repulse

Meaning: a substance used to repel something

Part of speech: noun

Example: Insect repellent is useful in summer.

Category: Science

Synonyms:

• deterrent
• repulsant

Meaning: To make an exact copy of something.

Part of speech: verb

Example: Scientists aim to replicate the experiment to verify the results.

Category: Science › Research

Synonyms:

• duplicate
• copy

Meaning: To run something again.

Part of speech: verb

Example: They decided to re-run the experiment to verify the results.

Category: Science

Synonyms:

• repeat
• replay

Antonyms: stop

Meaning: The systematic investigation into a subject.

Part of speech: noun

Example: Her research focused on climate change.

Category: Science › General Research

Synonyms:

• study
• investigation

Antonyms: ignorance

Meaning: Remaining after the main part has gone or been subtracted.

Part of speech: adjective

Example: The residual effects of the medication were minimal.

Category: Science › Chemistry

Synonyms:

• remaining
• leftover

Antonyms: total

Meaning: The remaining part of something after the main part has gone.

Part of speech: noun

Example: There was a residue of sugar at the bottom of the cup.

Category: Science › Chemistry

Synonyms:

• remnant
• remainder

Antonyms: whole

Meaning: The ability to withstand something.

Part of speech: noun

Example: The resistance of the material to heat is impressive.

Category: Science › Physics

Synonyms:

• opposition
• defiance

Antonyms: compliance

Meaning: Having the ability to resist something.

Part of speech: adjective

Example: Water-resistant materials are useful for outdoor gear.

Category: Science

Synonyms:

• resistant
• impervious

Meaning: The quality of being deep, full, and reverberating.

Part of speech: noun

Example: The resonance of her voice filled the room.

Category: Science › Physics

Synonyms:

• echo
• vibration

Meaning: The outcome of an action or event.

Part of speech: noun

Example: The result of the test was better than expected.

Synonyms:

• outcome
• consequence

Antonyms: cause

Meaning: Occurring as a result of something.

Part of speech: adjective

Example: The resultant changes improved the system.

Category: Science

Synonyms:

• consequential
• subsequent

Meaning: To come back to the surface after being submerged.

Part of speech: verb

Example: The diver will resurface after exploring the wreck.

Category: Science

Synonyms:

• reappear
• emerge

Meaning: To slow down or delay the progress of something.

Part of speech: verb

Example: The heavy rain may retard the construction schedule.

Category: Science

Synonyms:

• delay
• hinder

Antonyms: accelerate

Meaning: The action of delaying or slowing down.

Part of speech: noun

Example: The retardation of the project was due to funding issues.

Category: Science

Synonyms:

• delay
• hindrance

Meaning: Slowed down or delayed in progress.

Part of speech: adjective

Example: The retarded growth of the plant was concerning.

Category: Science

Synonyms:

• delayed
• slowed

Meaning: Moving backward or in reverse.

Part of speech: adjective

Example: The retrograde motion of the planet was observed.

Category: Science › Astronomy

Synonyms:

• backward
• receding

Meaning: To move in a circular or curved path around a central point.

Part of speech: verb

Example: The planets revolve around the sun.

Category: Science

Synonyms:

• rotate
• spin

Antonyms:

• stay
• remain