firm up

verb

To make (tentative plans) more definite.

“Let me know as soon as your plans firm up.”

Meanings

verbfirm up (third-person singular simple present firms up, present participle firming up, simple past and past participle firmed up)

present singular third person firms up · participle present firming up · participle past firmed up · past firmed up

  1. idiomatictransitiveTo make (tentative plans) more definite.

    Can we firm up plans for the barbecue Sunday?

    2 more examples

    1977-1980, Lou Sullivan, personal diary, quoted in 2019, Ellis Martin, Zach Ozma (editors), We Both Laughed In Pleasure Just got a call from Falces office firming up my hospital date.

    Sometime soon (if it isn't happening already), Labour leader Sir Kier Starmer and his team will be firming up plans for what they want to do in the crucial first 100 days of a new government.

    2023 September 6, Nigel Harris, “Comment: Leaderless and rudderless”, in RAIL, number 991, page 3
  2. idiomaticintransitiveTo become more definite.

    Let me know as soon as your plans firm up.

  3. transitiveTo make (muscles) more toned through physical exercise.

    He hopes to firm up his biceps a bit before meeting the girls.

  4. intransitiveTo become more toned through physical exercise.

    After weeks of working out, his biceps finally began to firm up a bit.

  5. intransitiveTo become firmer in consistency.

    Cook the omelet until the top has started to firm up.

Synonyms & antonyms

Also see

Translations

French préciser, affermir
  • préciserTo make tentative plans more definite
  • affermirTo make muscles more toned
Irish cruaigh
  • cruaighTo become firmer in consistency
Cite this entry
APA

firm up. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/firm%20up

MLA

“firm up.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/firm%20up. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “firm up,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/firm%20up.

Source: firm up on Wiktionary, CC BY-SA 4.0.