Affluent, a.
Etymology: [Cf. F. affluent, L. affluens, -entis, p. pr. See Affluence.]
1. Flowing to; flowing abundantly. "Affluent blood." Harvey.
2. Abundant; copious; plenteous; hence, wealthy; abounding in goods or riches. Language . . . affluent in expression. H. Reed. Loaded and blest with all the affluent store, Which human vows at smoking shrines implore. Prior.
1 other Webster entry under this spelling
Affluent, n.
A stream or river flowing into a larger river or into a lake; a tributary stream.
Shades of meaning
Fernald has no entry of its own for affluent; he lists it under plentiful.
Where he writes about it:
That is ample which gives a safe, but not a large, margin beyond a given demand; that is abundant, affluent, bountiful, liberal, plentiful, which is largely in excess of manifest need. — from plentiful
Affluent and liberal both apply to riches, resources; liberal, with especial reference to giving or expending. (Compare synonyms for adequate.) Affluent, referring especially to riches, may be used of thought, feeling, etc. — from plentiful
Neither affluent, copious, nor plentiful can be used of time or space; a field is sometimes called plentiful, not with reference to its extent, but to its productiveness. — from plentiful