An Italian-American slang word used to describe an on-the-side girlfriend.
Strangely, this word originates from "comare," which is a word for the godmother of one's child. Alternatively, the godfather of one's child is a "compare."
These words are also used to describe a very close friend who isn't necessarily the godmother of your children.
"I don't trust anyone more than my goomara when it comes to taking care of my baby."
"He's not here with his wife tonight, but his goomara, instead."