29 August 2007
This phrase meaning to be on the run from something is U.S. criminal slang from the turn of the 20th century. From Appleton’s Popular Science Monthly of April 1897:
To do a lam, meaning to run.
And from 1904 we have this from Life in Sing Sing by “Number 1500”:
He plugged the main guy for keeps and I took it on a lam for mine.
The verb to lam, meaning to escape, to run away is somewhat older. From Allan Pinkerton’s 1886 Thirty Years A Detective:
After he has secured the wallet he will…utter the word “lam!” This means to let the man go, and to get out of the way as soon as possible.
This slang usage probably comes from the English dialectical verb lam meaning to thrash or to strike and was used in parallel to beat it. This verb lam may ultimately be of Scandinavian origin; the Old Norse lemja means to lame, but the connection cannot be conclusively established.
Sources:
Oxford English Dictionary, 2nd Edition, 1989.
Historical Dictionary of American Slang.