'brainiac' is a correct and usable word in written English.
You can use it to respectfully refer to someone who is particularly smart or intelligent. For example, you might say, "My friend is such a brainiac - she got the highest score on the test!".
The latter was eventually revealed to be a creation of perennial Superman villain Brainiac.
Maybe it is a look that your face saves on the off-chance that something particularly bizarre and exciting might happen to you... like finding out that you have been invited to speak in front of hundreds of people at a Cambridge University debate for example, and pitted against the brainiac national treasure Stephen Fry no less... My name is Kissy Sell Out.
Despite injury and depression, Hank brings down a vast drug ring, even when he discovers that the kingpin is his own brother-in-law, a sneering brainiac who has always considered himself superior.
His indelible performance as Mark Zuckerberg, in "The Social Network," suggested that a new kind of personality had entered the world, a code-based brainiac who deals with life as if it were data.
Seemingly, it can only conceive of a writer's persona as one thing at a time: a prick, a detached brainiac, a suffering saint.
People complained that it was because of her brainiac mythic stuff, her interest in image and symbol, that the show was so expensive and so delayed.
By the time you realize that you want more of his angularity of body and mind, though, Urbaniak (rhymes with "brainiac") has probably already moved on to embody other ideas, in front of other people.
"You're a little brainiac, you".
8 P.M. (FX) MEGAMIND (2010) Will Ferrell lends his voice to this movie's blue-tinted, egg-headed title character, a hypersensitive brainiac who faces an existential crisis after one of his grandiose, evil schemes to vanquish his nemesis, the Elvis-coiffed Metro Man (Brad Pitt), actually works.
We'd rather be in a brainiac competition than a wallet competition.
