monomeaner 

A single person who who is mean to others for no reason or purpose

John is a monomeaner because he calls Sam a fag for no reason at all

monomeaner by Herbalife lover January 14, 2016

Monomester 

One term, instead of something like 'trimester'. Can describe school years that are broken up into more than one part.

It's the second monomester of the year.
This monomester is the hardest one!

Monomester by BlancoOso June 13, 2011

Monomemer 

A poster on social media who reposts the identical meme excessively and/or repeatedly to the point that it is considered spam. (adj. monomemic)

Jack3tball7 was such an irritating monomemer that I blocked him, because his rude, repeating meme was eating up too much space in the thread.

Monomemer by Great Grape Ape June 15, 2014