镰刀是一种收割的工具，由一片弯曲的刀片（刀刃在内）和手柄组成。用时一手持手柄，刀片放平，一手持农作物禾草等，镰刀向内用力。

镰刀从石器时代开始使用。铁镰刀、大镰从铁器时代出现。西元前3500年，农民就开始使用镰刀、西元前1298年 - 1235年壁画中也出现过镰刀。

A sickle is a hand-held agricultural tool with a variously curved blade typically used for harvesting grain crops or cutting succulent forage chiefly for feeding livestock (either freshly cut or dried as hay).

A great diversity of types is used across many cultures. Between the dawn of the Iron Age and present, hundreds of region-specific variants of this basic forage-cutting tool were forged of iron, later steel.