Noun
A cantankerous person.
You are an old sourbelly this evening. What's the matter? — John Dos Passos, Michael Clark, Streets of Night (1990)
Alternative spelling of sowbelly
Their supplies were down to a dog tent, five plugs of chewing tobacco, four beans, and a slab of sourbelly. — Walter Vaughan, The Life and Work of Sir William Van Horne (1920)