Etymology
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lambaste (v.)
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). 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.
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paste (v.2)

"hit hard," by 1846, probably an alteration of baste "beat" (see lambaste) influenced by some sense of paste (n.1). Related: Pasted; pasting.

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lam (n.)
"flight, escape," as in on the lam, 1928, in pickpocket slang, (according to OED attested from 1897 in do a lam), from a U.S. slang verb meaning "to run off" (1886), of uncertain origin, but perhaps from lam (v.), which was used in British student slang for "to beat" since 1590s (compare lambaste); if so, the word has the same etymological sense as the slang expression beat it.
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