LATIN DICTIONARYLexicon Latīnum
adjectivefirst/second-declension adjective

triangulus

triangulus (feminine triangula, neuter triangulum)
Classical[triˈaŋ.ɡʊ.ɫʊs]Ecclesiastical[triˈaŋ.ɡu.lus]

Meaning

  1. adjectivetriangular, three-cornered, three-sided

In the readers how our graded readers gloss it

Declension

singular
formmasculinefeminineneuter
nominativetriangulustriangulatriangulum
genitivetriangulītriangulaetriangulī
dativetriangulōtriangulaetriangulō
accusativetriangulumtriangulamtriangulum
ablativetriangulōtriangulātriangulō
vocativetrianguletriangulatriangulum
plural
formmasculinefeminineneuter
nominativetriangulītriangulaetriangula
genitivetriangulōrumtriangulārumtriangulōrum
dativetriangulīstriangulīstriangulīs
accusativetriangulōstriangulāstriangula
ablativetriangulīstriangulīstriangulīs
vocativetriangulītriangulaetriangula

trĭangŭlus, a, um, adj. tres-angulus,
I. having three corners or angles, threecornered, triangular.
I. Adj.: sidera, Cic. Div. 2, 42, 89: forma cutis, Cels. 7, 25, 2: species (Siciliae), Plin. 3, 8, 14, § 86: ager, Col. 5, 2, 5: latera radicis, id. 13, 11, 218 et saep.—
II. Substt.
a. trĭangŭlum, i, n., a triangle: quadrata amplius spatium complectuntur triangulis, Quint. 1, 10, 41; so id. 1, 10, 3; Cic. N. D. 2, 49, 125; Plin. 27, 8, 39, § 61.—
b. trĭangŭlus, i, m., a triangle, Front. Expos. Form. pp. 32, 33, 35 Goes.

Origins

  1. Proto-Indo-European*tréyes
  2. Proto-Italic*trejes
  3. Proto-Italic*trēs
  4. Latintriangulus

Proto-Indo-European *h₂eng- Proto-Indo-European *h₂engulos Proto-Italic *angulos Latin angulus Latin triangulus Derived from trēs (“three”) + angulus (“angle, corner”).

Quick answers

What does triangulus mean in Latin?
triangulus, a adjective, means “triangular, three-cornered, three-sided”.
How do you pronounce triangulus?
In classical Latin, [triˈaŋ.ɡʊ.ɫʊs]; in ecclesiastical (church) Latin, [triˈaŋ.ɡu.lus].
Where does triangulus come from?
Proto-Indo-European *tréyes → Proto-Italic *trejes → Proto-Italic *trēs → Latin triangulus.