trigonaalse
Trigonaalse is the genitive singular form of the Estonian adjective trigonaalne, which means trigonal or triangular—describing shapes, figures, or properties that have three angles or threefold symmetry. In technical contexts the base form trigonaalne is used to describe related concepts, while trigonaalse appears when the adjective modifies a noun in the genitive case, for example in phrases like trigonaalse nurga omadused (features of a triangular angle) or trigonaalse süsteemi omadused (features of a trigonal system).
Etymology and form: trigonaalne derives from the Estonian prefix-trigon combination referring to three and the concept
Usage and domains: The term is common in mathematics, crystallography, mineralogy, and related sciences where threefold
See also: trigonal, triangular, kolmnurk (triangle), trigonometria.