a type of conic map projection in which the parallels are represented as arcs of circles having centers at different points along the straight central meridian and the other meridians are shown as curves
See polyconic projection in American Heritage Dictionary 4
(pŏlˌē-kŏnˈĭk)
noun
A conic map projection having distances between meridians along every parallel equal to those distances on a globe. The central geographic meridian is a straight line, whereas the others are curved and the parallels are arcs of circles.