Definitions
1.nounAn motor with hemispherical combustion chambers. A piston engine internal combustion engine with hemispherical piston cylinder heads.
2.nounA combustion chamber with the hemispherical cylinder head from such an engine.
3.nounA hemispherical cylinder head from such a motor.
4.nounA vehicle equipped with such a motor engine.
5.noun(by extension) Domed versions of the above that have cylinder heads that are not exactly hemispherical