egg and dart in American English
noun: a design for enriching an ovolo or echinus, consisting of a closely set, alternating series of oval and pointed forms
egg and dart in British English
a decorative molding used in architecture and cabinetwork, consisting of an egg-shaped form alternating with a form shaped like an arrow, anchor, or tongue
noun: an ornamental moulding in which a half egg shape alternates with a dart, tongue, or anchor shape