triagonal
Triangular, trigonal.
Adjective
- Triangular, trigonal.
- [T]he greatest part of the face, nay, of the head, was nothing else but two large and protuberant bunches […] shap'd into a multitude of small Hemispheres, plac'd in a triagonal order […]. - 1665, Robert Hooke,...
- 2005, LazyTown (TV series), "Dear Diary" (season 1, episode 16): "The Mine Song" This mailbox is mine And this triagonal sign. That blue balloon, the month of June. They're mine, mine, mine, mine, mine.
Origin
Irregular formation of trigonal, after tetragonal etc.