Old English swin "pig, hog, wild boar," from Proto-Germanic *sweina- (source also of Old Saxon, Old Frisian Middle Low German, Old High German swin, Middle Dutch swijn, Dutch zwijn, German Schwein, Old Norse, Swedish, Danish svin), neuter adjective (with suffix *-ino-) from PIE *su- "pig" (see sow (n.)). The native word, largely ousted by pig. Applied to persons from late 14c. Phrase pearls before swine (mid-14c.) is from Matthew vii.6; an early English formation of it was:
Ne ge ne wurpen eowre meregrotu toforan eowrum swynon. [c. 1000]
The Latin word in the Gospel verse was confused in French with marguerite "daisy" (the "pearl" of the field), and in Dutch the expression became "roses before swine." Swine-flu attested from 1921.
herd n.1
Old English heord "herd, flock, company of domestic animals," also, rarely, "a keeping, care, custody," from Proto-Germanic *herdo (source also of Old Norse hjorð, Old High German herta, German Herde, Gothic hairda "herd"), from PIE *kerdh- "a row, group, herd" (source also of Sanskrit śárdhah "herd, troop," Old Church Slavonic čreda "herd," Greek korthys "heap," Lithuanian kerdžius "shepherd"). Of any animals, wild or domestic, from c. 1200; of people, often in a disparaging sense, from c. 1400. Herd instinct in psychology is first recorded 1886.