look up any word, like bukkake:
 
1.
1. A chick so hot she makes superman or you weak in the noggin

2. Something so cool or good that it makes you weak in the noggin (can't think so straight)
i was at this strip club this weekend and there was this babe who without a doubt was kryptonic...too bad she was dumb as a box o rocks
by Big BNP January 29, 2004
 
2.
A verb describing anyone who uses their power or authority to make you or your (planned) actions inferior, weakened or subject to being dominated or overthrown, or that renders your ability to do something obsolete.
Despite turning 18 and having new superpowers (the ability to go clubbing and drinking legally) my Kryptonic mother won't even let me leave the house at night to do such acts.
by LanksEO March 27, 2009