knuckle up

verb

To clench one's fist(s) as though in preparation for a fight.

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Meanings

verbknuckle up (third-person singular simple present knuckles up, present participle knuckling up, simple past and past participle knuckled up)

present singular third person knuckles up · participle present knuckling up · participle past knuckled up · past knuckled up

  1. informalchiefly African-American VernacularTo clench one's fist(s) as though in preparation for a fight.

    With a resolve to get his son away from these monsters, Isaac knuckled up and mean-mugged his opponent.

    2012, Vanessa Miller, Latter Rain
    1 more example

    Tony stumbled a little and when he found his balance, he knuckled up and sent a jab toward Will's neck.

    2012, Pink Maxwell, A Scorpion's Sting, page 209
  2. broadlyinformalTo approach a problem aggressively.
  3. slangTo strike or fight.
Cite this entry
APA

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

MLA

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

Chicago

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

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