sull noun (rare) a sulky fit, a ‘sulk’. 1972 E. Welty Optimist's Daughter ii. iv. 97 He's been in a sull ever since you married Judge McKelva and didn't send him a special engraved invitation to the wedding. Eudora Welty was an accomplished author, and this is an example of using a verb as a noun. Maybe it's something she heard in real life.
the meaning of "sull" in this sentence: "He’s been in a sull"