Origin: 1595–1605; < Latintrepidātiōn- (stem of trepidātiō), equivalent to trepidāt(us) (past participle of trepidāre to hurry, alarm; see trepid, -ate1) + -iōn--ion
1605, from L. trepidationem (nom. trepidatio) "agitation, alarm, trembling," noun of action from pp. stem of trepidare "to tremble, hurry," from trepidus "alarmed, scared," from PIE *trep- "to shake, tremble" (cf. Skt. trprah "hasty," O.C.S. trepetati "to tremble"), related to *trem- (see tremble).