There is a word for a quarter of a circle or a plane: "quadrant".
What is the corresponding word for a third of a circle? "tridrant" or "terdrant" or something different?
There's no word that I'm aware of that means a third of a circle. We have quadrant (1/4), sextant (1/6) and octant (1/8) but nothing for a third beyond the generic term: a sector.
You could call it a one-third sector or a 120 degree sector.
Based on numerical prefixes, if there was such a word it would be 'tridant' but this isn't a word you'll find in any dictionary and most people would assume you'd misspelled 'trident'.
- an aspect of 120° (one third of a circle).
However this is a fairly obscure word, I think.
Edit: upon further inspection it appears this word refers to a group of three, not a single third.
trine (trīn) n.
A group of three.
In astrology, the aspect of two planets when 120° apart.