Placed in or among, or put between, as if ingrained or woven in: specifically noting a bone of the lower jaw of fishes interposed between others.n. A bone of the lower jaw or mandibular arch of some vertebrates, as fishes, between the hyomandibular bone above and the quadrate bone below, forming an inferior ossification of the suspensorium of the lower jaw, articulated or ankylosed with the quadrate or its representative. Also called mesotympanic. See cuts under palatoquadrate and teleost.