Halichondriae \Hal`i*chon"dri*[ae]\ (h[a^]l`[i^]*k[o^]n"dr[i^]*[=e]), prop. n. pl. [NL., fr. Gr. "a`ls, "alo`s, sea + cho`ndros cartilage.] (Zool.) An order of sponges, having simple siliceous spicules and keratose fibers; -- called also {Keratosilicoidea}. [1913 Webster]