adjective Date: 1878 of, relating to, or being the division of the hexagonal crystal system or the forms belonging to it characterized by a vertical axis of threefold symmetry, ~ly adverb
TRIGONAL
Meaning of TRIGONAL in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012