shelfyoudaoicibaDictYouDict[shelf 词源字典]
shelf: [14] Shelf appears to have been borrowed from Middle Low German schelf ‘shelf’. This may have come from the Germanic base *skelf- ‘split’, which also produced Old English scylfe ‘partition’, the word’s underlying meaning therefore being a ‘piece of split wood used for standing things on’. The derivative shelve dates from the 16th century.
[shelf etymology, shelf origin, 英语词源]
shelf (n.)youdaoicibaDictYouDict
late 14c., from Middle Low German schelf "shelf, set of shelves," or from Old English cognate scylfe, which perhaps meant "shelf, ledge, floor," and scylf "peak, pinnacle," from Proto-Germanic *skelf- "split," possibly from the notion of a split piece of wood (compare Old Norse skjölf "bench"), from PIE root *(s)kel- (1) "to cut, cleave" (see scale (n.1)).

Shelf life first recorded 1927. Phrase on the shelf "out of the way, inactive" is attested from 1570s; of unmarried women with no prospects from 1839. Off the shelf "ready-made" is from 1936. Meaning "ledge of rock" is from 1809, perhaps from or influenced by shelf (n.2). Related: Shelves.
shelf (n.2)youdaoicibaDictYouDict
"sandbank," 1540s, of unknown origin. Related: Shelfy "abounding in sandbanks."