"one who complains," early 15c., agent noun from groan (v.).
Entries linking to groaner
groan v.
Old English granian "to utter a deep, low-toned breath expressive of grief or pain; to murmur; to lament," from Proto-Germanic *grain- (source also of Old Norse grenja "to howl"), of imitative origin, or related to grin (v.). Meaning "complain" is from early 13c., especially in Middle English phrase grutchen and gronen. As an expression of disapproval, by 1799. Related: Groaned; groaning.