[au.di.ble] adj [LL audibilis, fr. L audire to hear; akin to Gk aisthanesthai to perceive, Skt avis evidently] (1529): heard or capable of being heard -- au.di.bil.i.ty n -- au.di.bly adv
[2]audible n (1962): a substitute offensive or defensive play called at the line of scrimmage in football