noun. In entomology, the modified fore wing of beetles or Coleoptera, forming with its fellow of the opposite side a hard, horny, or leathery case or sheath, more or less completely covering and protecting the posterior membranous wings when these are folded at rest, and usually forming an extensive portion of the upper surface of a beetle; a shard.

noun. In some chætopodous annelids, as the Aphroditidæ, or polychætous annelids, as the Polynoë, one of the squamous lamellæ overlying one another on the dorsal surface of the worm, made by a modification of the dorsal cirri of the parapodia, of which they are thus specialized appendages.

noun. See the adjectives.

"The elytrum, which is heavier and much less extensive, repeats this structure."

Elysium  electrum  elytra