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.
mid-13c., "to watch over or herd (livestock);" of animals, "gather in a herd, go in a herd, form a flock," late 14c. From herd (n.1). Transitive sense of "to form (animals, people, etc.) into a herd" is from 1590s. Related: Herded; herding.
"keeper of a flock of domestic animals," Old English hierde, from the source of herd (v.). Now obsolete except in compounds. Compare Old Saxon hirdi, Middle Dutch hirde, German Hirte, Old Norse hirðir.