1. adjective Utterly bizarre, disproportionate, or disfigured in appearance, as suggestive of genetic mutation. The creature had these mutant eyes, all misshapen and quivering, that didn't blink so much as roll back into their sockets briefly every few seconds.

2. adjective Extremely and abnormally large, especially that which grows in the ground. My uncle won another prize at the country fair for the mutant pumpkins he's been growing.

3. noun Someone or something that is bizarre, disproportionate, or disfigured in appearance, as suggestive of genetic mutation. Would you look at the size of that mutant! He must be nearly eight feet tall! As if I would be caught dead on a date with an ugly mutant like him!