from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The curve traced out by points P and Pˌ which lie on lines through a fixed point A where the midpoint M of PPˌ is on a fixed line and the absolute value }PM} = the absolute value }PˌM} = the absolute value }MO}, where O is the projection of A onto that fixed line.
from The Century Dictionary and Cyclopedia
- n. A nodal plane cubic curve which is the locus of a focus of a conic whose directrix and two tangents are given.
- n. A curve which is the locus of intersections of two lines rotating uniformly with commensurable velocities. See also suhstrophoid.
Greek strophos, twisted cord (from strephein, to turn) + -oid.(American Heritage® Dictionary of the English Language, Fourth Edition)
Common decency and good taste prevents us from displaying Freeth’s supertrisectrix strophoid.
But Freeth’s nephroid is something altogether different: a strophoid of a circle with a double curlicue in the kidney crotch.