Old English heran (Anglian), (ge)hieran, hyran (West Saxon) "to hear, listen (to), obey, follow; accede to, grant; judge," from Proto-Germanic *hauzjan (cf. Old Norse heyra, Old Frisian hora, Dutch horen, German hören, Gothic hausjan), perhaps from PIE *kous- "to hear" (see acoustic). The shift from *-z- to -r- is a regular feature in some Germanic languages.
For spelling, see see head (n.); spelling distinction between hear and here developed 1200-1550. Old English also had the excellent adjective hiersum "ready to hear, obedient," literally "hear-some" with suffix from handsome, etc. Hear, hear! (1680s) was originally imperative, used as an exclamation to call attention to a speaker's words; now a general cheer of approval. Originally it was hear him!