A guisarme (sometimes gisarme, giserne or bisarme) is a pole weapon used in Europe primarily between 1000-1400. Like many medieval polearms, the exact form of the weapon is hard to define from literary references, and the identification of surviving weapons can be speculative. Two main modern schools of thought exist:

1. Like most polearms the guisarme was developed by peasants by combining hand tools with long poles: in this case by putting a pruning hook onto a spear shaft. While hooks are fine for unsaddling horsemen from their mounts, they lack the stopping power of a spear especially when dealing with static opponents. While early designs were simply a hook on the end of a long pole, later designs implemented a small reverse spike on the back of the blade. Eventually weapon makers incorporated the usefulness of the hook in a variety of different polearms, and guisarme became a catch-all for any weapon that included a hook on the blade. This is exemplified by the terms bill-guisarmes, voulge-guisarmes, and glaive-guisarmes.
2. An alternative definition is given by Ewart Oakeshott in his book European Weapons and Armour. He sees the guisarme as a "crescent shaped double socketed axe" on a long shaft. His primary reason is the use of the term "giserne" and axe interchangeably for the same weapon in the poem Sir Gawain and the Green Knight. Strengthening his view are the illustrations in the original manuscript which clearly show Sir Gawain with a long crescent shaped axe (see right). In his novel Knight in Anarchy, George Shipway describes the process of training for a judicial duel using the guisarme, where he favours the double-socketed axe interpretation of the weapon.