n. In the sponge-spicules, a threerayed element having the arms of equal length and sloping from the point of union.Having three feet or legs.n. In classical antiquity, a seat, table, or other article resting on three feet.n. Hence, any object having three feet or legs, as a three-legged stool.n. A three-legged frame or stand, usually jointed at the top, for supporting a theodolite, compass, camera, or other instrument. See cuts under rock-drill and transit.n. In anatomy and zoology, a tripodal formation; a three-pronged or triradiate structure, as a bone. The premaxillary bone of birds is a tripod.