MEANING: adjective: Unskilled; unscrupulous; incompetent.
noun: An unskilled or unscrupulous worker.

ETYMOLOGY: From jack (man, worker) + blackleg. Earliest documented use: 1839

JOCKLEG - what Eddie Arcaro used, to urge his horse to run faster

TACKLEG - the portion of the America's Cup course that's heading into the wind

J.C. KLEG - putative founder of Kleg's Hardware Store