Antiprism is a term used to describe a polyhedron that has two parallel, congruent bases connected by a set of congruent triangular faces. Some synonyms for antiprism include: 1. Bipyramid - a polyhedron with two congruent polygonal bases and triangular faces that connect them. 2. Dipyramid - another term for bipyramid, referring to a polyhedron with two identical polygonal bases and triangular faces. 3. Trapezohedron - a polyhedron with four trapezoid-shaped faces and two congruent polygonal bases. 4. Disphenoid - a skewed antiprism where the two bases are not parallel to each other, resulting in a twisted shape.