birdbrain vs addlehead

birdbrain and addlehead both are nouns.

Word	Noun	Adjective	Verb	Adverb
birdbrain	Yes	No	No	No
addlehead	Yes	No	No	No

As nouns, birdbrain and addlehead are synonyms defined as:

birdbrain and addlehead: a person with confused ideas; incapable of serious thought

Other synonyms of birdbrain include addle-head, loon.

birdbrain (noun)	addlehead (noun)
a person with confused ideas; incapable of serious thought	a person with confused ideas; incapable of serious thought