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A word used in conversation of siblings to complain about their mother. Comes from "mom" + "monster" = momster.
The momster is really angry tonight...
by Kitten123 July 10, 2005
A term of endearment for your dear mom.
"A puppy for Christmas?! Thanks Momster, it's just what I always wanted!"
by LaurenLEE December 16, 2008
A mom who is extremely scary, or scary looking.
Boy: Dude, that hag is a total momster!
by Notorious VIC January 24, 2010
An active member of the mommy mafia. (A mobster in the mommy mafia.)
"She's a new member of the West Oak Mommy Mafia - a momster in training."
by Regan and Lisa Brunsvold December 28, 2007
n. a social networking site for moms of teens and tweens powered by Family Circle magazine
Instead of joining facebook, I'm going to join Momster to connect with other moms like me.
by momstermanda January 07, 2010
“Momsters” are hip, tattooed, irreverent, sex-positive mothers who care for their children with an alternative, holistic approach to parenting, often frowned upon by modern day June Cleaver clones.
Hey man, look at that momster over there with her boob in that baby's mouth! Who do you think does her ink?
by MILF and Cookies March 16, 2014
A momster is something your mother can turn into when she flips her shit and freaks out at you. This normally happens when:

1) you cut your own hair
2) you pierce yourself
3) when you break something

4) when you accidently say something in front of her that is more of a "friend remark"
or 5) when you accidently drop your guinea pig that she really loves to feed.
teenager: "hey mom nice new computer charger" *poke* *crash* D= "umm....te-he-he-he..." *runs in room...followed by a mom...*

Momster: "YOU %^&* TEENAGER touchin' on my effing charger!!!!! AHHHerrrrrrrHAhbdsfjdkjf..."

teenager: "0_o holy shit, my mom just turned into a momster and flipped her shit.. "
by Magentaa0_o September 12, 2011