noun Slang.
- a clumsy, awkward person.
- a stupid or foolish person; blockhead.
noun
- US and Canadian slang a clumsy or stupid person
1967, American English, from Yiddish klots “clumsy person, blockhead,” literally “block, lump,” from Middle High German klotz “lump, ball.” Cf. German klotz “boor, clod,” literally “wooden block” (cf. clot).