to remain silent or hold oneself aloof in a sullen, ill-humored, or offended mood

Promise me that you won't sulk if I want to leave the party early.

a state or fit of sulking.

sulks, ill-humor shown by sulking

to be in the sulks.

Also, sulker. a person who sulks.

verb

be happy , grin , smile

verb

be down in the mouth , be in a huff , be morose , be out of sorts , be silent , brood , frown , gloom , glower , gripe , grouse , grump * , look sullen , lower , moon * , mope * , scowl , take on , mope , pet , pout , grumble , grump , moue