Adage, n.
Etymology: [F. adage, fr. L. adagium; ad + the root of L. aio I say.]
An old saying, which has obtained credit by long use; a proverb. Letting "I dare not" wait upon "I would," Like the poor cat i' the adage. Shak.
Syn. -- Axiom; maxim; aphorism; proverb; saying; saw; apothegm. See Axiom.
Shades of meaning
Fernald has no entry of its own for adage; he lists it under proverb.
Where he writes about it:
The proverb or adage gives homely truth in condensed, practical form, the adage often pictorial. — from proverb
"Hope deferred maketh the heart sick" is a proverb; "The cat loves fish, but dares not wet her feet," is an adage. — from proverb
Both the proverb and the adage, but especially the latter, are thought of as ancient and widely known. — from proverb