Simple Definition of knucklehead

from our Learner's Dictionary

knucklehead

noun

ˈnʌkəlˌhɛd

plural knuckleheads

US, informal : a stupid person : dummy

Don't be such a knucklehead.

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“Knucklehead.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/knucklehead. Accessed 11 Jun. 2026.

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