glue n.

Old English clæg "stiff, sticky earth; clay," from Proto-Germanic *klaijaz (source also of Old High German kliwa "bran," German Kleie, Old Frisian klai, Old Saxon klei, Middle Dutch clei, Danish klæg "clay;" also Old English clæman, Old Norse kleima, Old High German kleiman "to cover with clay").

Some sources see these as being from a common PIE root meaning "slime; glue" also forming words for "clay" and verbs for "stick together." Compared words include Latin gluten "glue, beeswax;" Greek gloios "sticky matter;" Lithuanian glitus "sticky," glitas "mucus;" Old Church Slavonic glina "clay," glenu "slime, mucus;" Old Irish glenim "I cleave, adhere;" Old English cliða "plaster." But Beekes writes that "Not all comparisons are convincing," and notes that most words cited are from Balto-Slavic or Germanic, "which suggests European substrate origin."

In Scripture, the stuff from which the body of the first man was formed; hence "human body" (especially when dead). As an adjective, "formed of clay," 1520s. Clay-pigeon "saucer of baked clay used as a flying target in trap-shooting," in place of live birds, is from 1881. Feet of clay "fundamental weakness" is from Daniel ii.33.

1580s, "unite or cause to adhere," from Latin agglutinatus, past participle of agglutinare "fasten with glue," from ad "to" (see ad-) + glutinare "to glue," from gluten "glue" (from PIE *glei-; see glue (n.)). Related: Agglutinated; agglutinating. Perhaps suggested by the earlier use of the same word in English as a past-participle adjective (1540s) "united as by glue," from the Latin past participle.