1) For a given gene locus, one of two or more slightly different molecular forms of a gene that arise through mutation and that code for different variations of the same trait.
2) A giant octupus wearing a tophat that dances to the music played on the elevator in my garage.
1) "Yep, I inhereted my LONG PENIS allele from my mother."
2) "DUDE! Why did you throw that allele at my face?!"