DANDY. That’s the dandy; i.e. the ton, the clever thing; an expression of similar import to “That’s the barber.”

DANDY. In 1820, a fashionable non-descript. Men who wore stays to give them a fine shape, and were more than ridiculous in their apparel.

Now a DANDY’s a thing, describe him who can?
That is very much made in the shape of a man;
But if for but once could the fashion prevail,
He’d be more like an APE if he had but a tail.

I’m sure with the DANDIES we well may dispense,
As neither possessing wit, learning, nor sense;
And if in such follies they still will persist,
Throw them all in the Thames, and they’ll never be miss’d.

Source: Francis Grose, Pierce Egan: Grose’s Classical Dictionary of the Vulgar Tongue. London, 1823.