Triangulum

noun

Tri·​an·​gu·​lum trī-ˈaŋ-gyə-ləm 

astronomy

: a small northern constellation that is visible between the constellations of Andromeda and Aries and that is represented by the figure of an isosceles triangle

Triangulum: A small constellation, its name comes from its three brightest stars, which form a long and narrow triangle.

—Graham Henry, South Wales Echo, 20 Jan. 2012

Word History

First Known Use

1695, in the meaning defined above

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