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3.
A person whose attempt at intelligence fails spectacularly. Usually used sarcastically in the phrase "what a brainiac".
"...and then his entire system crashed. What a brainiac."
by John May 12, 2004
 
1.
smart person
Bush isn't a brainiac
by Anonymous January 30, 2003
 
2.
1: A British Television show that was bought by G4TV, which contains funny, stupid, and just plain unneeded science experiments. It often involves the use of breasts.

2: Someone who's life is dedicated to accumulation of all the world's knowledge.

3: A big waste of -The Omega Master's time.
"Did you see Brainiac last night? That chick was hot!!!"

"Ned is too freaking smart, a regular Brainiac."

"Why did I even bother to post up Brainiac?"-The Omega Master
by -The Omega Master September 02, 2005
 
4.
This term applies to people who are extremely intelligent. If a brainiac were a superhero, their brain would definitely be their secret weapon.
My boss Paul is such a brainiac I don't ever have to use Google, HE is my human Google.
by MereBear803 April 18, 2011
 
5.
Term of mild disrespect used to describe bright, studious people, such as scientists, chess-players or spelling bee champions. Plural of brainiac. Synonymous with certain usages of brain, geek, nerd etc.
Only brainiacs hang out at the library for fun.
by Linton November 06, 2003
 
6.
Someone who is addicted to getting head.
Girls love Metaphor and I love em back, addicted to getting head, chicks call me the brainiac.

From the Boondocks on Adult Swim

by DiDo25878 December 11, 2007
 
7.
sarcastic. used when denoting someone's lack of intelligence, i.e. they try an idea and it fails miserably.
"Nice Job, brainiac." emphasis must be put on 'brainiac' or else it loses its effectiveness.
by Tengu March 31, 2005