Why is the ninth month called September?
1560s, from Middle French cone (16c.) or directly from Latin conus "a cone, peak of a helmet," from Greek konos "cone, spinning top, pine cone," perhaps from PIE root *ko- "to sharpen" (cf. Sanskrit sanah "whetstone," Latin catus "sharp," Old English han "stone").
A solid body having a circle for its base and sides inclined so as to meet at a point above the base.
See cone cell.