Meaning

noun a very light colorless element that is one of the six inert gasses; the most difficult gas to liquefy; occurs in economically extractable amounts in certain natural gases (as those found in Texas and

originFrom New Latin helium, from Ancient Greek ἥλιος (hḗlios, “sun”) (because its presence was first theorised in the Sun's atmosphere) with the suffix + -ium. Probably coined by Norman Lockyer. This suffix is unusual, because it is usually used only for metallic elements. It is likely that Lockyer, being an astronomer, was unaware of the usual chemical conventions.

Etymology from Wiktionary, CC BY-SA 3.0