Trignomial 

Three gnomes in a circle uttering incantations to summon a spectre of the deep.

like a pentagram with three gnomes, instead of five people.
The trignomial's summoned a cowzoon from the deep.

Trignomial by MooseWheat March 19, 2010

Trinomical 

A ungrateful little shit who never thanks anyone for the nice things they have done for him and is all around a horrible human being

Trinomical: Go suck my dick you never do anything for me
Nice Guy: I got you dark souls 3
Trinomical : Fuck you

Trinomical by DJMoonMan June 16, 2016

Trinomial 

An expression that is a sum or difference of three terms. Usually factored by the Maagic X method.

x² - 7x + 10
Student A: How do I factor this trinomial?!
Student B: Use the Maagic X method!

Trinomial by mathwoman October 25, 2010

trigonial 

An adjective describing a three plane, three-dimensional object.

This rugby ball was constructed with three identically curved pieces. Therefore it is trigonial.

trigonial by Jerome Myer June 10, 2020