Covered in hair—literally "bearlike" (compare "bovine", cowlike; "hircine", goatlike). Not just the chest, or armpit hair or anything overgrown. The whole body. They'd have to be pretty damn hairy to be considered hirsute.
Usage: yo, ninjamonkee123, joe mama is one hirstute fatty bizzle, she's so hairy, she can grow corn in that field - if the damn crabs didn't eat it.