loon vs idler

loon and idler both are nouns.

Word	Noun	Adjective	Verb	Adverb
loon	Yes	No	No	No
idler	Yes	No	No	No

As nouns, idler is a hypernym of loon; that is, idler is a word with a broader meaning than loon:

Other hypernyms of loon include bum, do-nothing, layabout, loafer.

loon (noun)	idler (noun)
large somewhat primitive fish-eating diving bird of the Northern Hemisphere having webbed feet placed far back; related to the grebes	person who does no work
a worthless lazy fellow
a person with confused ideas; incapable of serious thought