prius n.

"that which takes precedence, that which necessarily goes before," noun use of Latin neuter of prior (adj.) "former, earlier" (see prior (adj.)). The hybrid car (with a capital P- ) debuted in 1997 in Japan, 2001 in U.S. and Europe. The name supposedly was chosen because the car was regarded as a predecessor of new types. The classically proper plural of the car name is said to be Priora, but that is for the adjective.