synaptic Syllabification: (syn·ap·tic)Pronunciation: /səˈnaptik/Definition of synaptic adjective Anatomy of or relating to a synapse or synapses between nerve cells:the synaptic membraneDerivatives synapticallyPronunciation: /-ik(ə)lē/ adverb synaptic in other Oxford dictionaries Definition of synaptic in the British & World English dictionary