Also non-hyphenated, maternoincestuant.

A person who engages in incestuous relations with his own mother. Sometimes referred to as a motherfucker.

The term may have use as in insult.
Tom's not very smart. If we call him a materno-incestuant, he probably wouldn't know what it means.
by dword August 6, 2008
Like family game night but...
Those aren't dice in gramma's hands...
That's not a spinner in mom's hand...
and that's DEFENITELY not a penis you're inserting into your sisiter's vagina. Oh wait... yes it is.
Usually includes statutory rape and pedophillia.
"Can me and sis sleep over at the couisns, their mom said we're gonna have a ALOT of fun.
by Niloc February 22, 2005
The (extreme) reinforcement (read: over-hyping) of ideas and/or beliefs that occurs when like-minded people communicate with each other.
Meeting Chairperson: Tonight, we're going to discuss the genius of President George Bush... (to person leaving) Excuse me, where are you going?

Smart person leaving: Someplace where I won't get brain damaged from the impending incestuous amplification.
by Man-Machine November 2, 2007
Being in a state of sexual attraction or taking fancy in a step sibling.
Justin is scared that him having sex with his soon to be step sister would be consider step-incestuous.
by SlaveMatthews September 24, 2014
When a younger sibling has relations with her more senior sibling. Strictly related to Girls.
Did you see that "Incestuous Armati"?

Yeah she totally face raped her sister!
by Sue da nim September 20, 2010
The act of having sex with one's clone.
Question: Is having sex with one's clone incest or masturbation?
Answer: It's neither. It's narcisso-incestuous masturbation.
by mysticalcupcake April 17, 2009
A person who has sex with their dead father.
That dude is such an incestuous homo necro.
by Traction November 4, 2007