Sharp-ended stone tools resembling a knife are often categorized as point in abroad, however, in Japan they are separated from double-edged spear points and only single-edged tools are referred as stone tools resembling a knife.
海外では先端の尖ったナイフ形石器を尖頭器に含んで扱うことが多いが、日本では両刃の槍先形尖頭器とは区別して片刃の利器をナイフ形石器と呼称する。