Meaning

noun a cylinder of calcium carbonate hanging from the roof of a limestone cave

originFrom New Latin stalactites, from Ancient Greek σταλακτός (stalaktós, “dripping; dropping”) + Latin -ītēs (suffix with the sense ‘belonging to’ forming adjectives) (modelled after the names of stones ending in -ites). Σταλακτός (Stalaktós) is derived from σταλάσσειν (stalássein, “to drip; to let (something) drip”) + -τός (-tós, suffix forming adjectives denoting possibility from verbs).

Etymology from Wiktionary, CC BY-SA 3.0