Murrsuit is an term used by furries to cover various types of costumes when used or constructed for sexual purposes, including both regular fursuits and some made of lycra/spandex, PVC, leather or rubber.
The term is derived from "murr", an expression often used within furry fandom, usually as a sound of contentment (similar to purr), but sometimes to indicate sexual interest or arousal (the use of "murr" in this manner is often considered facetious, demeaning, or both).
Difference between murrsuits and fursuits
A murrsuit refers to fursuits of a sexual nature. Several fursuit builders are known to make such suits, though not all will advertise their willingness to do so. Others are home-made, or alterations of an existing suit with an SPH and/or SPA (though builders will often void any warranty on a suit which has been modified or used for sexual activity).
Some have used the term "murrsuit" to refer to any fursuit that has been worn while having sex, irrespective of the suit's construction.