phase in

verb

To introduce (something) little by little, either via discrete phases of increase or (by extension) by continuous gradations; to introduce in phases, or as if by phases (gradually); to begin (something) gradually.

“The program phased in last year.”

Opposite
phase out
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Meanings

verbphase in (third-person singular simple present phases in, present participle phasing in, simple past and past participle phased in)

present singular third person phases in · participle present phasing in · participle past phased in · past phased in

  1. transitiveTo introduce (something) little by little, either via discrete phases of increase or (by extension) by continuous gradations; to introduce in phases, or as if by phases (gradually); to begin (something) gradually.

    The program phased in last year.

    1 more example

    The government will phase in the new education system over a period of three years.

    Antonyms: phase out

Synonyms & antonyms

verbTo introduce (something) little by little, either via discrete phases of increase or (by extension) by continuous gradations; to introduce in phases, or as if by phases (gradually); to begin (something) gradually.

Opposite
phase out

More synonyms by meaning

verbintroduce gradually

Opposite
phase out
Broader
introduceinnovate
Also see
run in

Synonym sets from Open English WordNet, CC BY 4.0.

Cite this entry
APA

phase in. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/phase%20in

MLA

“phase in.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/phase%20in. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “phase in,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/phase%20in.

Source: phase in on Wiktionary, CC BY-SA 4.0.