A word that should be in the dictionary. Means shall not, or in simple english, won't.
I shalln't kill the zebra.
Aa acutal word used in Shakespeare's era by everyone. All the time. All day. 24/7. Means: Shall not.
Aimee shalln't disbelieve Jasmine's vocabulary knowledge from now on, because now she owes her a milkshake.