A contraction of shall not.
Source: Webster's dictionaryIn the next world, I shan't be doing music, with all the striving and disappointments. I shall be being it. Ralph Vaughan Williams
Unlike my subject will I frame my song, It shall be witty, and it shan't be long. Philip Stanhope, 4th Earl of Chesterfield
I shan't be lonely now. I was lonely; I was afraid. But the emptiness and the darkness are gone; when I turn back into myself now I'm like a child going at night into a room where there's always a light. Edith Wharton
I'm going out to clean the pasture spring I'll only stop to rake the leaves away (And wait to watch the water clear, I may) I shan't be gone long. You come too. Robert Frost
Last Words in a Suicide note I feel certain that I'm going mad again. I feel we can't go thru another of those terrible times. And I shan't recover this time. I begin to hear voices. Virginia Woolf
If you don't work you shan't eat. African Proverb