Pronunciation: (gren"u-dēr'),[key] —n. 1. (in the British army) a member of the first regiment of household infantry (Gren'adier Guards'). 2. (formerly) a specially selected foot soldier in certain elite units.
3. (formerly) a soldier who threw grenades.
4. Also calledrat-tail,rat tail. any of several deep-sea fishes of the family Macrouridae, having an elongated, tapering tail.