trigon（n.）
"triangle," in various specialized senses, 1560s, from Latin trigonum (in anatomy) or directly from Greek trigōnon (neuter trigōnos) "a triangle," noun use of adjective meaning "triangular, three-cornered;" from treis "three" (see tri-) + -gōnos "angled" (from PIE root *genu- (1) "knee; angle").
Used in astronomy and surveying, and as a word-forming element in zoology and paleontology. Related: Trigonous; trigonic.
该词起源时间：1560年代