alarmed (adj.)youdaoicibaDictYouDict[alarmed 词源字典]
"disturbed by prospects of peril," 1640s, past participle adjective from alarm (v.).[alarmed etymology, alarmed origin, 英语词源]
blight (n.)youdaoicibaDictYouDict
1610s, origin obscure; according to OED it emerged into literary speech from the talk of gardeners and farmers, perhaps ultimately from Old English blæce, blæcðu, a scrofulous skin condition and/or from Old Norse blikna "become pale." Used in a general way of agricultural diseases, sometimes with suggestion of "invisible baleful influence;" hence figurative sense of "anything which withers hopes or prospects or checks prosperity" (1828). Compare slang blighter. Urban blight attested by 1935.
prospect (n.)youdaoicibaDictYouDict
early 15c., "act of looking into the distance," from Latin prospectus "distant view, look out; sight, faculty of sight," noun use of past participle of prospicere "look out on, look forward," from pro- "forward" (see pro-) + specere "look at" (see scope (n.1)). Meaning "extensive view of the landscape" is from 1530s; transferred sense of "mental view or survey" is from 1620s. Sense of "person or thing considered promising" is from 1922. Prospects "expectations, things looked forward to" is from 1660s.
prospect (v.)youdaoicibaDictYouDict
"explore for gold, examine land with a view to a mining claim," 1841, from prospect (n.) in specialized sense of "spot giving prospects of ore" (1832). Earlier in a sense "look forth, look out over" (1550s), from Latin prospectare. Related: Prospected; prospecting.
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.