Noun
heliair (plural heliairs)
(underwater diving) A mixture of helium, nitrogen and oxygen, used as a breathing gas instead of normal air.
Heliair will always have less than 21% oxygen, and will be hypoxic (less than 17% oxygen) for mixes with more than 20% helium. Source: Internet
Heliair blends are similar to the standard Trimix blends made with helium and Nitrox 32, but with a deeper END at MOD. Source: Internet