n. In anatomy and zoology: The lower leg; the part of the hind limb between the knee and the ankle; the second segment of the hind limb, corresponding to the forearm or antebrachium of the fore limb, represented by the length of the tibia or shinbone.n. Some part likened to a leg, as one of a pair of supporting parts; a pillar; a peduncle.n. plural The calcareous brachial supports in the Brachiopoda, as in Pentamerus and Rhynchonella, where they are a pair of short discrete, slightly curved lamellæ. Also called crural plates.