American English

Definition of brainiac noun from the Oxford Advanced American Dictionary

 

brainiac

 noun
noun
NAmE//ˈbreɪniˌæk//
 
(informal)
 
jump to other results
a very intelligent person A team of brainiacs are here to answer your scientific questions. Brainiacs from around the world take part in the contest. From the name of a character in the Superman stories.
See the Oxford Advanced Learner's Dictionary entry: brainiac