manic depressive illness vs bipolar disorder

manic depressive illness and bipolar disorder both are nouns.

Word	Noun	Adjective	Verb	Adverb
manic depressive illness	Yes	No	No	No
bipolar disorder	Yes	No	No	No

As nouns, manic depressive illness and bipolar disorder are synonyms defined as:

manic depressive illness and bipolar disorder: a mental disorder characterized by episodes of mania and depression

Other synonyms of manic depressive illness include manic-depressive psychosis, manic depression.

manic depressive illness (noun)	bipolar disorder (noun)
a mental disorder characterized by episodes of mania and depression	a mental disorder characterized by episodes of mania and depression