Pronunciation: (kō-hēr'unt, -her'-),[key] —adj. 1. logically connected; consistent: a coherent argument. 2. cohering; sticking together: a coherent mass of sticky candies. 3. having a natural or due agreement of parts; harmonious: a coherent design. 4. Physics,Optics.of or pertaining to waves that maintain a fixed phase relationship, as in coherent light. Cf. laser.