A klutz is a person who is clumsy, foolish, inept, or accident-prone. The term is perhaps derived from the Yiddish קלאָץ klots ('wooden beam'), cognate with the GermanKlotz, meaning a "block" or "lump". The British slang, pillock and the Australian slang, galah are used with similar meaning, particularly in terms of being foolish and inept.
The term klutz has largely permeated into the English language, even amongst speakers of English with no Yiddish or indeed Jewish heritage.
Klutz Press is an imprint of Scholastic Press. John Cassidy has used the coincidence of the name of the publisher and the Yiddish word to exploit the title in some of his books, for instance Juggling for the Complete Klutz.