(grous) noun plural grouse
Any of a family (Tetraonidae) of game birds of the northern hemisphere, related to the pheasants, smaller than the domestic hen, and having mottled plumage; especially, the red grouse (Lagopus scoticus) of the British Isles, the ruffed grouse or partridge (Bonasa umbellus) of the United States, the pinnated grouse or prairie chicken (Tympanuchus cupido), the sage grouse or cock of the plains, the spruce grouse or spruce partridge (Canachites canadensis), and the capercaillie. [Origin uncertain]

(grous) Slang v.i. groused, grous·ing
To grumble; grouch. [<OF grousser murmur]
—grous′er noun
—grous′ing noun