phase

B2 · Upper Intermediate Countable noun Science Technical

n. the changing shape of the bright part of the moon or a planet.

n. the particular appearance of a celestial body's illuminated disk in a recurring cycle.

“The moon is in its crescent phase tonight.”

“Astronomers track the lunar phases to predict tidal patterns and optimal conditions for deep-space observation.”

C1 · Advanced Countable noun Science Academic · Technical

n. a state of matter, such as being a solid, liquid, or gas.

n. a physically distinctive form of matter, such as a solid, liquid, gas, or plasma.

“When water boils, it changes from a liquid phase to a gas phase.”

“The experiment demonstrated how the substance remains stable in its solid phase even under extreme atmospheric pressure.”

C1 · Advanced Countable noun Science Academic · Technical

n. a specific point in a repeating movement, like a wave or vibration.

n. the position of a point in time on a waveform cycle.

“If two sound waves are out of phase, they can cancel each other out.”

“The engineers adjusted the signal timing to ensure the two oscillators remained in phase, preventing destructive interference.”

B2 · Upper Intermediate

v. to start or stop something in gradual steps rather than all at once.

v. to introduce or withdraw something in planned stages; typically used with 'in' or 'out'.

“The company will phase out the old software over the next six months.”

“The government plans to phase in the new tax regulations over a three-year period to minimize the economic impact on small businesses.”