Either of the horny front wings in beetles and some other insects which cover and protect the functional hind wings WordNet 3.0 & Open English WordNet

An elytron is a modified, hardened forewing of beetles, though a few of the true bugs such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra, and in most species only the basal half is thickened while the apex is membranous, but when they are entirely thickened the condition is referred to as "coleopteroid". Wikipedia

A modified hardened forewing in certain insect orders Wikipedia Disambiguation

Hardened forewing of certain insect orders, notably beetles Wikidata

A modified, hardened forewing of certain insect orders. OmegaWiki