(physics) The normal isotope of helium, ⁴₂He, that has two neutrons

(physics) The rare isotope of helium, ³₂He, that has a single neutron

plural of helium star

plural of helium variable

(inorganic chemistry) Ellipsis of helium hydride cation. The unstable binary cation HeH⁺ present in interstellar space. It is the strongest acid, reactive with every chemical species except positive ions, including electrons.

plural of helium flash

(technical diving, saturation diving, underwater diving) Synonym of helium descrambler

(technical diving, saturation diving, underwater diving) An electronic device that lowers the pitch of speech, to compensate for the high-pitched speech of someone breathing in a helium atmosphere breathing mix (ie. heliox, heliair, ...), so as to be understandable to other people.

(physics) Having the electronic structure of a helium atom

Synonym of helide