Meaning

noun flesh of any of various grouse of the family Tetraonidae; usually roasted; flesh too dry to broil

noun popular game bird having a plump body and feathered legs and feet

verb hunt grouse

originUncertain; possibly from British dialectal groosh (“excellent, very good”) (Lothian (Scotland)), grosh (northeast Lancashire) and groshy (“having thriving vegetation; juicy and tender; of weather: good for vegetation, rainy”) (Lancashire, Yorkshire), grushie (“having thriving vegetation”) (Scotland); from Scots groosh (“excellent, very good”) (Lothian, obsolete), grush (obsolete), grushie, grushy…

Etymology from Wiktionary, CC BY-SA 3.0