Webster’s Revised Unabridged Dictionary · 1913
Generatrix
Gen′er·a′trix (·ā′trĭks), n.; pl. L. Generatrices (#), E. Generatrixes (#). [L.] (Geom.) That which generates; the point, or the mathematical magnitude, which, by its motion, generates another magnitude, as a line, surface, or solid; — called also describent.