the GNU version of the Collaborative International Dictionary of English
adj. Cleft to the middle, or slightly beyond the middle, into three parts; three-cleft.
The Century Dictionary and Cyclopedia
Divided into three parts.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. divided into three lobes
Word Usage
"El – Yitm, appeared to be of great height; we all remarked its towering stature and trifid headpiece, apparently upwards of five thousand feet high, before we had heard the tale attached to it."