E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Having distinctive piquancy, as racy wine. It was first applied to wine, and, according to Cowley, comes to us from the Spanish and Portuguese raiz (root), meaning having a radical or distinct flavour; but probably it is a corruption of relishy (French, reléché, flavorous).
Rich, racy verse, in which we see
The soil from which they come, taste, smell, and see.