From PIE *h₂ḱous- (to perceive by ear) — the same root that, through Greek, gave English 'acoustic.'
To perceive sound with the ear; to listen to and understand.
From Old English hieran (also hyran, heran) meaning to hear, to listen to, to obey — the obedience sense survives in hearken — from Proto-Germanic *hauzijanam (to hear), from PIE *h2kous- (to hear, to perceive through sound). The PIE root *h2kous- generated Latin audire (to hear) — an unexpected connection since audire and hear look nothing alike in their modern forms — and Greek akouein (to hear), ancestor of acoustic, acoustics, and acousmata (things heard in Pythagorean initiation). The Germanic branch retained the *h2 consonant as h, while the Latin branch