lanceolate

keihään muotoinen puhekieltä Having the general shape of a lance; much longer than wide, with the widest part lower than the middle and a pointed apex.
puhekieltä Of a class of knapped stone points, made without a stem, shoulders, notches, or other features that aid in attachment to a shaft.
2011, (w), The Origin of Our Species, Penguin 2012, p. 127:

The stone tools in these levels include Still Bay points, beautifully shaped thin lanceolate spear points, flaked on both sides.