twibill

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Archaic A battle-ax with two cutting edges.
2. n. Archaic A mattock with one blade like an ax and the other like an adz.

Century Dictionary and Cyclopedia

1. n. A double-bladed battle-ax, especially that carried by the Northern nations. Such battle-axes are often mentioned in literature, although but few heads of double axes have been found among thousands of other types. Compare Danish ax (under Danish), and ax.
2. n. A broadsword: so called from a misunderstanding of the word. See the quotation.
3. n. A kind of double ax; a kind of mattock the blade of which has one end shaped like an ax and the other like an adz.
4. n. A mortising-tool.
5. n. A reaping-hook.
6. n. Same as roaring boy (see roaring).

Wiktionary

1. n. An axe with two cutting blades
2. n. A mattock
3. n. 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 bisaigue (or besaigue)
4. n. obsolete A double-bladed halberd or battle-axe