The Spanish word 'selenita' comes from Ancient Greek origins, tracing back to 'σεληνίτης' (selenítes), meaning 'of the moon' or 'moonstone'. This Greek word was derived from 'Σελήνη' (Selene), which was both the name of the moon goddess in Greek mythology and the word for 'moon' itself. The Spanish term maintained these lunar associations, coming to mean both a moon dweller (someone who hypothetically lives on the moon) and selenite (a crystalline mineral with a moon-like luster).

Some related Spanish words include 'selenio' (selenium, the chemical element named after the moon due to its similarity to tellurium, which was named after the Earth) and 'selenografía' (selenography, the study of the moon's physical features). These words share the same Greek root relating to the moon.

English speakers might recognize this word's connection to several scientific terms: 'selenium' (the chemical element), 'selenology' (the study of the moon), and 'selenite' (the mineral). All these words share the same Greek root 'Selene', referring to the moon. The English word 'selenite' is a direct cognate of the Spanish 'selenita', both preserving the ancient connection to the moon in their meanings.