TRILATERAL
trilateral, triangular, three-sided
(adjective) having three sides; “a trilateral figure”
trilateral
(adjective) involving three parties; “trilateral talks”
triangle, trigon, trilateral
(noun) a three-sided polygon
Source: WordNet® 3.1
Etymology
Adjective
trilateral (not comparable)
Having three sides
Involving three parties
Source: Wiktionary
Tri*lat"er*al, a.Etym: [L. trilaterus; tri- (see Tri-) + latus,
lateris, side: cf. F. trilatéral. See Lateral.] (Geom.)
Definition: Having three sides; being three-sided; as, a trilateral
triangle.
– Tri*lat"er*al*ly, adv.
– Tri*lat"er*al*ness, n.
Source: Webster’s Unabridged Dictionary 1913 Edition