touchyoudaoicibaDictYouDict[touch 词源字典]
touch: [13] The etymological notion underlying touch seems to be the ‘striking of a bell’. It comes via Old French tochier from Vulgar Latin *toccāre ‘hit, knock’, which appears originally to have denoted ‘make the sound toc by striking something, such as a bell’ (as in English ticktock). The connection with bells is preserved in tocsin ‘signal given with a bell’ [16], which comes via French tocsin from Provençal tocasenh, a compound formed from tocar ‘strike’ and senh ‘bell’ (a relative of English sign).

Another member of the family is toccata [18], a borrowing from Italian, which etymologically denotes the ‘touching’ of the keys of an instrument with the fingers.
=> toccata, tocsin[touch etymology, touch origin, 英语词源]
touch (v.)youdaoicibaDictYouDict
late 13c., "make deliberate physical contact with," from Old French tochier "to touch, hit, knock; mention, deal with" (11c., Modern French toucher), from Vulgar Latin *toccare "to knock, strike" as a bell (source also of Spanish tocar, Italian toccare), perhaps of imitative origin. Related: Touched; touching.

From c. 1300 in transitive sense "bring into physical contact," also "pertain to." Other senses attested from 14c. are "perceive by physical contact, examine by sense of touch," also "be or come into physical contact with; come to rest on; border on, be contiguous with;" also "use the sense of touch," and "mention, describe." From early 14c. as "affect or move mentally or emotionally," with notion of to "touch" the heart or mind. Also from early 14c. as "have sexual contact with." Meaning "to get or borrow money" first recorded 1760. Touch-and-go (adj.) is recorded from 1812, apparently from the name of a tag-like game, first recorded 1650s. Touch football is first attested 1933. Touch-me-not (1590s) translates Latin noli-me-tangere.
touch (n.)youdaoicibaDictYouDict
c. 1300, from Old French toche "touch, a touching; a blow, attack; a test" (Modern French touche), from tocher "to touch" (see touch (v.)). Meaning "slight attack" (of an illness, etc.) is recorded from 1660s. Sense of "communication" (to be in or out of touch) is from 1884. Sense of "skill or aptitude in some topic" is first recorded 1927, probably from music or the arts. Soft touch "person easily manipulated" is recorded from 1940.