Simple Definition of knucklehead

from our Learner's Dictionary

knucklehead

noun

plural knuckleheads
US, informal : a stupid person : dummy
Don't be such a knucklehead.

Cite this Entry

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

More from Merriam-Webster on knucklehead

More from Merriam-Webster