lamster

Lamsters as a class are probably as old as the law from which they flee, but the term lamster didn't sneak into our language until the early 1900s, less than ten years after the appearance of the earliest known evidence of the noun lam, meaning "sudden or hurried flight especially from the law" (as in the phrase "on the lam"). Both words have an old verb relation, though. Lam has meant "to beat soundly" or "to strike or thrash" since the late 16th century (and consequently gave us our verb lambaste), but in the late 19th and early 20th centuries it developed another meaning: "to flee hastily." The origins of the verb are obscure, but etymologists suggest that it is Scandinavian in origin and akin to the Old Norse lemja, meaning "to thrash."