orthotriæne

from The Century Dictionary.

• noun A caltrop in which one of the arms is very long and straight. See caltrop, 4.
• noun In the nomenclature of sponge-spicules, a triæne whose three cladi or prongs project at right angles with the shaft; a simple spicule of the rhabdus type, trifurcate or with three secondary rays at one end, and these rays at light angles with the shaft.