safeyoudaoicibaDictYouDict[safe 词源字典]
safe: [13] Like save, and indeed salvage and salvation, safe comes from Latin salvus ‘uninjured’. It reached English via Old French sauf. Salvus itself went back to a prehistoric Indo-European *solwos ‘whole’, which came from the same base that produced English soldier, solemn, and solid. The noun safe ‘strongbox’ [15] was originally save, a derivative of the verb, but by the late 17th century it had, under the influence of the adjective, become safe.

The plant-name sage [14] comes via Old French sauge from Latin salvia, etymologically the ‘healing’ plant, a derivative of salvus (English acquired salvia itself in the 19th century).

=> sage, salute, salvage, salvation, salvia, save, soldier, solemn, solid[safe etymology, safe origin, 英语词源]
safe (n.)youdaoicibaDictYouDict
"chest for keeping food or valuables," early 15c., save, from Middle French en sauf "in safety," from sauf (see safe (adj.)). Spelling with -f- first recorded 1680s, from influence of safe (adj.).
safe (adj.)youdaoicibaDictYouDict
c. 1300, "unscathed, unhurt, uninjured; free from danger or molestation, in safety, secure; saved spiritually, redeemed, not damned;" from Old French sauf "protected, watched-over; assured of salvation," from Latin salvus "uninjured, in good health, safe," related to salus "good health," saluber "healthful," all from PIE *solwos from root *sol- "whole" (cognates: Latin solidus "solid," Sanskrit sarvah "uninjured, intact, whole," Avestan haurva- "uninjured, intact," Old Persian haruva-, Greek holos "whole").

As a quasi-preposition from c. 1300, on model of French and Latin cognates. From late 14c. as "rescued, delivered; protected; left alive, unkilled." Meaning "not exposed to danger" (of places) is attested from late 14c.; of actions, etc., "free from risk," first recorded 1580s. Meaning "sure, reliable, not a danger" is from c. 1600. Sense of "conservative, cautious" is from 1823. Paired alliteratively with sound (adj.) from late 14c. The noun safe-conduct (late 13c.) is from Old French sauf-conduit (13c.).