X-chrome 

noun; A word used to describe someone who is extremely stupid with an excessively large forehead. Also known as a five-head. The word comes from the appearance of Down Syndrome in the person. Down syndrome is caused by something like an extra chromosome, so X-chrome is just an easier way to say extra chromosome.

Damn, John is such an X-chrome. I've never seen any with as big a forehead or as stupid as him.

X-chrome by Asschafing January 5, 2009

x chromosome 

Chromosome which is found in both males and females. XY = male. XX = female. Sperm can be either an X or Y chromosome. During fertilization, if the Y chromosome sperm reaches the egg, then the baby is a boy. If the X chromosome sperm reaches the egg, then the baby is a girl.

Think of it as females having two copies of the same CD music album in every cell in their body, while males have one copy of that album in every cell in their body(x chromosome) and an extra single CD (the y chromosome) also in every cell in their body.

Even if the y chromosome was suffering from genetic degredation(which it is not) the effect could easily be reversed by genetic engineering.

x chromosome by John Ronane April 8, 2004

x chromosone 

Something no one seems to have anymore.

"hello class today were going to talk about this shitty x chromosone which none of you have anymore you dumb fucks."

x chromosone by Dr Death 2.0 August 23, 2016