noun ·Rare ·Advanced level

Definitions

Noun

1. 1
   A horny, sulfur-containing protein, related to keratin, that forms the skeletal structure of certain classes of sponges. A proteinaceous compound of which the spicules in Demospongiae are composed.

Etymology

From sponge + -in.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.