hydrailEtymologyFrom hydro- + rail, coined in 2004 in the International Journal of Hydrogen Energy.hydrail means Any rail technology where vehicles use on-board hydrogen as a source of energy to power the motors. Lexicurio rates it Sui generis — a strength score of 89 out of 100.nounAny rail technology where vehicles use on-board hydrogen as a source of energy to power the motors.