clay (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."| pipe (n.) Old English pipe "simple tubular musical wind instrument," also "tube for conveying water," from Vulgar Latin pipa "a pipe, tube-shaped musical instrument" (source also of Italian pipa, French pipe, Old Frisian pipe, German Pfeife, Danish pibe, Swedish pipa, Dutch pijp), a back-formation from Latin pipare "to chirp or peep," of imitative origin.| wall (n.) Old English weall, Anglian wall "rampart, dike, earthwork" (natural as well as man-made), "dam, cliff, rocky shore," also "defensive fortification around a city, side of a building," an Anglo-Frisian and Saxon borrowing (Old Saxon, Old Frisian, Middle Low German, Middle Dutch wal) from Latin vallum "wall, rampart, row or line of stakes," apparently a collective form of vallus "stake," from PIE walso- "a post." Swedish vall, Danish val are from Low German. Meaning "interior partition of a structure" is mid-13c.