twibill (plural twibills)
- An axe with two cutting blades.
- A mattock.
- A double-bladed tool used in gate-type hurdle-making for cutting out mortices, with a flat chisel and a mortice chisel or hook, similar to the much larger French carpenter's tool, the besaiguë (or bisaiguë).
- (obsolete) A double-bladed halberd or battle-axe.