Leuku is a Finnish word for a knife used mostly by Lappish people, Sami.

Traditional handmade leuku and puukko. Leuku is the bigger one

Leuku has a long, wide, and strong blade that is more suited for light chopping and shelter making than fine carving, so it is not well suited to whittling. It is used instead of an axe for firewood, wood clearing, bone-breaking, and other works. Typical leuku has a blade length ranging from 200 to 450 mm. Largest of the leukus actually can be considered as machetes or short swords. The handle of leuku is invariably made from birch. The tang runs through the handle. The handle has no crossguard. Traditional material for the sheath is reindeer leather.

The blade is often convex or flat grind, which gives the blade more toughness. Many leukus have fullers. Leuku is an excellent outdoor tool for bushcrafting.