trefoil arch(n = noun.artifact) - a pointed arch having cusps in the intrados on either side of the apex;
is a kind of pointed arch

abutment arch, alveolar arch, aortic arch, arch, arch brick, arch over, arch stone, arch support, basket-handle arch, bean trefoil, bell arch, bird's foot trefoil, branchial arch, broken arch, camber arch, corbel arch, diminished arch, drop arch, fallen arch, flat arch, four-centered arch, gill arch, gothic arch, haemal arch, hemal arch, horseshoe arch, in an arch manner, keel arch, lancet arch, lesser yellow trefoil, marsh trefoil, maya arch, mayan arch, metatarsal arch, moon trefoil, moorish arch, neural arch, ogee arch, pectoral arch, pelvic arch, pier arch, pointed arch, prairie bird's-foot trefoil, prairie trefoil, proscenium arch, rampant arch, roman arch, round arch, rowlock arch, safety arch, scheme arch, scoinson arch, sconcheon arch, segmental arch, semicircular arch, shouldered arch, skeen arch, skene arch, skew arch, steel arch bridge, stinking bean trefoil, straight arch, sunken arch, superciliary arch, three-centered arch, tick trefoil, trefoil, trimmer arch, triumphal arch, trumpet arch, tudor arch, vertebral arch, water trefoil, yellow trefoil, zygomatic arch