sulky

From sulk +‎ -y.

sulky (comparative sulkier, superlative sulkiest)

1. (often derogatory) silent and withdrawn after being upset

   the sulky child

   • 1865, Lewis Carroll, Alice's Adventures in Wonderland

     The first question of course was, how to get dry again: they had a consultation about this, and after a few minutes it seemed quite natural to Alice to find herself talking familiarly with them, as if she had known them all her life. Indeed, she had quite a long argument with the Lory, who at last turned sulky, and would only say, “I’m older than you, and must know better.” And this Alice would not allow, without knowing how old it was, and, as the Lory positively refused to tell its age, there was no more to be said.

   Synonyms: sullen, morose

A horse pulling a sulky

sulky (plural sulkies)

1. A low two-wheeled cart, used in harness racing.
2. Any carriage seating only the driver.