Cissoid
Pronunciation : Cis"soid
Part of Speech : n.
Etymology : [Gr. (Geom.)
Definition : Defn: A curve invented by Diocles, for the purpose of solving two celebrated problems of the higher geometry; viz., to trisect a plane angle, and to construct two geometrical means between two given straight lines.
Source : Webster's Unabridged Dictionary, 1913