tindol : constellation
The Illunse word for constellation is tindol. Tindol is an uncommon last name.
This word is a mixture of the Old English word tungol (luminary, star, planet, constellation) and the Latin word sidus (star; constellation).
tindolas : constellations
The Illunse word for constellations (nominative plural) is tindolas. In German tindolas means ivy gourds or scarlet gourds.
Constellations in Latin is sideris. The plural of tungol in Old English is tungol (same as the singular).
I didn't find a word for constellation in either Quenya or Sindarin. Although I did find names for several constellations, such as Orion and the Big Dipper, in Quenya.