Origin and history of lam

1630s, apparently from baste "to thrash" (see baste (v.3)) + the obscure verb lam "to beat, to lame" or the related Elizabethan noun lam "a heavy blow" (implied by 1540s in puns on lambskin), for which see lamb. "In sailors' use, to beat with a rope's end" [Century Dictionary].

Compare earlier lamback "to beat, thrash" (1580s, used in old plays). A dictionary from c. 1600 defines Latin defustare as "to lamme or bumbast with strokes." Related: Lambasted; lambasting.

"crippled or disabled by injury to or defect of a limb or limbs," especially "walking with difficulty," Middle English, from Old English lama "crippled, lame; paralytic, weak," from Proto-Germanic *lama- "weak-limbed," literally "broken." This is reconstructed (Watkins) to be from PIE root *lem- "to break; broken," with derivatives meaning "crippled" (source also of Old Church Slavonic lomiti "to break," Lithuanian luomas "lame").

In Middle English especially "crippled in the feet," but also "crippled in the hands; disabled by disease; maimed." The figurative sense of "imperfect, halting, defective in quality or quantity" is attested from late 14c. The sense of "socially awkward" is attested from 1942.

As a noun meaning "crippled persons collectively" it is attested from late Old English. To come by the lame post (17c.-18c.) was an old colloquialism in reference to tardy mails or news out-of-date.

Germanic cognates include Old Norse lami "lame, maimed," Dutch and Old Frisian lam, German lahm "lame."