1. Of or relating to a rocket propellant consisting of fuel and an oxidizer that ignite spontaneously on contact.
2. Using such a fuel.
[From German Hypergol, a hypergolic fluid propellant : from hyper-, extreme (from Greek huper-; see HYPER-) + Greek ergon, work; see ERG1.]
hyper·gol′ (hīpər-gôl′, -gōl′, -gŏl′) n.
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