1A knife with a semicircular blade set transversely to the handle, used chiefly in leather-working.
2A knife or machete having a blade with a backward-pointing spike, used by some headhunting tribes in Samoa and the Philippines; compare head-axe (now rare).
Origin
Late 17th century.
Definition of head knife in US English:
head knife
noun
1A knife with a semicircular blade set transversely to the handle, used chiefly in leather-working.
2A knife or machete having a blade with a backward-pointing spike, used by some headhunting tribes in Samoa and the Philippines; compare head-axe (now rare).