 The ending "ergol" is a combination of Greek "ergon" or work, and Latin "oleum" or oil, later influenced by the chemical suffix "-ol" from alcohol.Monergols were monopropellants, while non-hypergols were bipropellants which required external ignition, and lithergols were solid/liquid hybrids.Hypergolic propellants (or at least hypergolic ignition) were far less prone to hard starts than electric or pyrotechnic ignition.