A bill is a class of agricultural implement used for trimming tree limbs, which was often repurposed/modified for use as an infantry polearm. In English, the term 'Italian Bill' is applied to the similarly functioning ronche/runka/roncone. In contrast to the English bill, the Italian 'bill', (variously called the ronche, runka, or ronkone) tended toward 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. Bills were adapted to military use through addition of various projecting blades. Other variants include bill hook and bill-guisarme
The bill is similar in size, function and appearance to the halberd, and might be said to represent convergent evolution to fill a common niche: a pole-arm with a point to thrust with, a hook to drag with, and a spike/axe to cut with. The bill should not be conflated with a war-scythe, another pole-arm adapted from an agricultural implement, the scythe.
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 in 1513 was a classic match between continental-style pike 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. 
The shorthanded bills were used by the army of historic India as well, mainly by infantrymen of Bengal.
An agricultural version, commonly known as either a brush-axe or bush-axe, is readily available in rural hardware and farm-supply stores in the United States today, and is available in the United Kingdom as a "long bill". It has a 4-foot-long (1.2 m) handle, and a 16-inch (41 cm) head. It is 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-axe can fell a 3-inch (7.6 cm) tree with a single blow.
In Brazil the bill () is a very common tool in rural areas as tool and sometimes as a self-defense weapon.
- Stewart, A.T.Q (November 1995). The Summer Soldiers: 1798 Rebellion in Antrim and Down (paperback). Blackstaff Press Ltd. pp. 294. ISBN 0-85640-558-2.