The bill is a polearm weapon used by infantry in medieval Europe. The bill is similar in size, function and appearance to the halberd, differing mainly in the hooked blade form. Other terms for the bill include English bill, bill hook or bill-guisarme.
Derived originally from the agricultural billhook, the bill consisted of a hooked chopping blade with several pointed projections mounted on a staff. The end of the cutting blade curves forward to form a hook, which is the bill's distinguishing characteristic. In addition, the blade almost universally had one pronounced spike straight off the top like a spear head, and also a hook or spike mounted on the 'reverse' side of the blade. There were many types of bill. English bills tended to be relatively short, with broad chopping heads, while Italian bills (ronche) often had very long thrusting points. The English distinguished between several varieties of bill, including the black, brown and forest bills, but the differences between them are currently not fully understood.
George Silver, writing in 1599, stated that the (military) black bill should be 5 or 6 feet (1.5 or 1.8 m) long, while the (possibly civilian) forest bill should be 8 or 9 feet (2.4 or 2.7 m) long.
One advantage that it had over other polearms was that while it had the stopping power of a spear and the power of an axe, it also had the addition of a pronounced hook. If the sheer power of a swing did not fell the horse or its rider, the bill's hook was excellent at finding a chink in the plate armour of cavalrymen at the time, dragging the unlucky horseman off his mount to be finished off with either a sword, spear or the bill itself. These characteristics also made it effective against heavily armoured infantry, dragging them into the melee or exploiting the weak points in their armour. The small point found on the trailing edge of some bills was useful for puncturing armour as well—concentrating the force of the blow onto the point.
During the 16th century when most European states were adopting the pike and arquebus, the English preferred to stick with the combination of bill and English longbow. Even in the Tudor period, bills were still common with levies sent to fight the Scots. The Battle of Flodden (1513) was a classic match between Continental-style Pikes formations (Scots) and Billmen (English).
Although obsolete as a military weapon by the 17th century, bills were sent (along with other obsolete arms and armor) to the New World with English colonists to provide defense against Native Americans and Spanish military expeditions. Examples of bills have been excavated at the site of Jamestown, Virginia (established 1607). 
The shorthanded bills were used by the army of historic India as well, mainly by infantrymen of Bengal. Nowadays smaller versions are used as agricultural tools and as kitchen appliances.
An agricultural version, commonly known as either a brush-ax or bush-ax, is readily available in rural hardware and farm-supply stores in the United States today. It has a 4-foot-long (1.2 m) handle, and a 16-inch (41 cm) head. It is extremely useful for clearing undergrowth and unwanted hedgerows. Both the concave and convex edges may be sharpened edges, but spear-points and back-hooks are not available. Expertly used, the brush-ax can fell a 3-inch (7.6 cm) tree with a single blow. Inexpertly used, it can pose a grave danger of accidental maiming to those standing nearby.