yammer vs complain

yammer and complain both are verbs.

Word	Noun	Adjective	Verb	Adverb
yammer	No	No	Yes	No
complain	No	No	Yes	No

As verbs, complain is a hypernym of yammer; that is, complain is a word with a broader meaning than yammer:

Other hypernyms of yammer include kick, kvetch, plain, quetch, sound off.

yammer (verb)	complain (verb)
complain whiningly	express complaints, discontent, displeasure, or unhappiness
cry loudly, as of animals	make a formal accusation; bring a formal charge