(countable) Any of various game birds of the subfamily Tetraoninae which inhabit temperate and subarctic regions of the Northern Hemisphere; specifically, the red grouse (Lagopus lagopus scotica) native to heather moorland on the British Isles.

(uncountable) The flesh or meat of this bird eaten as food.

(intransitive) To hunt or shoot grouse.

(intransitive, originally military slang, informal) To complain or grumble.

(Australia, New Zealand, slang) Excellent.