pound (n.1) Look up pound at Dictionary.com
measure of weight, Old English pund "pound" (in weight or money), also "pint," from Proto-Germanic *punda- "pound" as a measure of weight (source of Gothic pund, Old High German phunt, German Pfund, Middle Dutch pont, Old Frisian and Old Norse pund), early borrowing from Latin pondo "pound," originally in libra pondo "a pound by weight," from pondo (adv.) "by weight," ablative of *pondus "weight" (see span (v.)). Meaning "unit of money" was in Old English, originally "pound of silver."

At first "12 ounces;" meaning "16 ounces" was established before late 14c. Pound cake (1747) so called because it has a pound, more or less, of each ingredient. Pound of flesh is from "Merchant of Venice" IV.i. The abbreviations lb., £ are from libra, and reflect the medieval custom of keeping accounts in Latin.
pound (n.2) Look up pound at Dictionary.com
"enclosed place for animals," late 14c., from a late Old English word attested in compounds (such as pundfald "penfold, pound"), related to pyndan "to dam up, enclose (water)," and thus from the same root as pond. Ultimate origin unknown; some sources indicate a possible root *bend meaning "protruding point" found only in Celtic and Germanic.
pound (v.) Look up pound at Dictionary.com
"hit repeatedly," from Middle English pounen, from Old English punian "crush, pulverize, beat, bruise," from West Germanic *puno- (cognates: Low German pun, Dutch puin "fragments"). With intrusive -d- from 16c. Sense of "beat, thrash" is from 1790. Related: Pounded; pounding.