Definition of Triangulum in US English:

Triangulum

proper noun

Astronomy
  • 1A small northern constellation (the Triangle), between Andromeda and Aries.

    1. 1.1as genitive Trianguli /trīˈaNGɡyəlē, -ˌlī/ Used with preceding letter or numeral to designate a star in the constellation Triangulum.
      ‘the star Beta Trianguli’

Origin

Latin.

Pronunciation

Triangulum

/trīˈaNGɡyələm/