Top Definition
Relationship of an individual's mother to his or her partner when no marriage has taken place (for legal or personal reasons).
Doug: Since we live in a state that doesn't recognize gay marriage, I'm not sure what to call your mother. She's not an 'in-law'...
Ed: Call her your mother-out-law. I'm sure she'll like that.
by Mother-out-law November 30, 2011

Free Daily Email

Type your email address below to get our free Urban Word of the Day every morning!

Emails are sent from We'll never spam you.