tri·corn also tri·corne 
(trīkôrn′)
(trīkôrn′)n.
A hat having the brim turned up on three sides.
adj.
Having three corners, horns, or projections.
[French tricorne, from Latin tricornis, three-horned : tri-, tri- + cornū, horn; see ker-1 in the Appendix of Indo-European roots.]
tricorn