Pol`y*con"ic (?), a. [Poly- +
conic.] Pertaining to, or based upon, many
cones.
Polyconic projection (Map Making), a
projection of the earth's surface, or any portion thereof, by which
each narrow zone is projected upon a conical surface that touches the
sphere along this zone, the conical surface being then unrolled. This
projection differs from conic projection in that latter assumes
but one cone for the whole map. Polyconic projection is that in use in
the United States coast and geodetic survey.