mensa
1 of 2noun (1)
men·sa
ˈmen(t)sə
plural mensas
-səz
or mensae in sense 1 -n(ˌ)sā,
in sense 2 -n(ˌ)sē,
-nˌsī sometimes -n(ˌ)sā
1
Roman Catholicism : the top of the altar
especially : the top or central slab upon which the eucharistic elements are placed
2
[New Latin, from Latin] : the grinding surface of a tooth
Mensa
2 of 2noun (2)
Men·sa ˈmen-sə 
astronomy
: a dim southern constellation that is visible near the south celestial pole between the constellations of Hydrus and Chamaeleon and that is held to be a representation of Table Mountain in South Africa
Table Mountain is a South African icon and the only natural site on the planet to have a constellation of stars named after it — Mensa, meaning "the table." 
Asia Pulse, 14 Nov. 2011
Asia Pulse, 14 Nov. 2011Mensa is one of the faintest constellations in the sky, with no stars brighter than magnitude 5.0. Carole Stott and Giles Sparrow, Starfinder, 2010
Carole Stott and Giles Sparrow, Starfinder, 2010
Word History
Etymology
Noun (1)
Medieval Latin, from Latin, table, from Old Latin, flat cake offered to the gods, perhaps from feminine of mensus, past participle of metiri to measure
First Known Use
Noun (2)
1847, in the meaning defined above