One of the eighty-eight constellations designated by the International Astronomical Union (IAU), it covers a keystone-shaped wedge of sky 153.5 square degrees in area.

Originally named "Montagne de la Table" or "Mons Mensae",[1] Mensa was created by Nicolas-Louis de Lacaille out of dim Southern Hemisphere stars in honor of Table Mountain, a South African mountain overlooking Cape Town, near the location of Lacaille's observatory.

[3] Sir John Herschel proposed shrinking the name to one word in 1844, noting that Lacaille himself had abbreviated some of his constellations thus.

Mensa is bordered by Dorado to the north, Hydrus to the northwest and west, Octans to the south, Chamaeleon to the east and Volans to the northeast.

[6] The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of eight segments.

[5][a] Lacaille gave eleven stars in the constellation Bayer designations, using the Greek alphabet to label them Alpha through to Lambda Mensae (excluding Kappa).

Stars as dim as these were not generally given designations; however, Gould felt their closeness to the South Celestial Pole warranted their naming.