Originally a Hebrew word, popularized in
English by the cartoonist Herb Gardner. A `sad sack,' a
loser, a person who can't make any thing or any situation
work right for him or her; unassertive, shy, timid. Reference: `The Joys of Yiddish,' by Leo Rosten. His definition is "An innocuous, ineffectual, weak, helpless or hapless unfortunate." There are other spellings also.