tocsin (n.)

early 13c., signe, "gesture or motion of the hand," especially one meant to express thought or convey an idea, from Old French signe "sign, mark," from Latin signum "identifying mark, token, indication, symbol; proof; military standard, ensign; a signal, an omen; sign in the heavens, constellation."

According to Watkins, literally "standard that one follows," from PIE *sekw-no-, from root *sekw- (1) "to follow." De Vaan has it from PIE *sekh-no- "cut," from PIE root *sek- "to cut" He writes: "The etymological appurtenance to seco 'to cut' implies a semantic shift of *sek-no- 'what is cut out', 'carved out' > 'sign'." But he also also compares Hebrew sakkin, Aramaic sakkin "slaughtering-knife," and mentions a theory that "both words are probably borrowed from an unknown third source."

It has ousted native token. By c. 1300 as "an indication of some coming event." The meaning "a visible mark or device having some special meaning" is recorded from late 13c.; that of "miraculous manifestation, a miracle demonstrating divine power" is from c. 1300. In reference to one of the 12 divisions of the zodiac, from mid-14c.

The sense of "inscribed board with a characteristic device attached to the front of an inn, shop, etc.," to distinguish it from others is recorded from mid-15c. The meaning "indicator, token or signal of some condition" (late 13c.) is behind sign of the times (1520s). The meaning "conventional mark or symbol in place of words" (in music, mathematics, etc., as in plus sign) is by 1550s. In some uses, the word probably is a shortening of ensign. 

c. 1300, touchen, "move or reach so as to make deliberate physical contact with; put hand or finger on (something) so as to feel; bring into physical contact;" 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), a word perhaps of imitative origin. Related: Touched; touching.

The passage of the sense 'knock, strike' into that of 'touch' (in Fr., etc.) is like that of Eng. 'thrust, push' into 'put': a stroke at its lightest is a mere touch. [OED, 1989]

Also from c. 1300 as "pertain to;" of fire, water, etc., "pass over." From mid-14c. as "come into or be in, incidental or involuntary physical contact" (with something). From late 14c. as "border on, be contiguous with or tangent to," also "extend to, reach, attain."

More broadly, "affect physically in some way by contact," early 14c.: especially "stain; affect injuriously, lay hands on for harm, make physical contact with in such a way as to cause injury or pain."

In broader or figurative senses, often non-physical, "handle or have to do with" (late 14c.), especially "meddle with, harm, injure." From late 15c. as "be felt as the concern of."

In reference to a musical instrument or tune, "strike the strings (later keys) of, play (on a stringed instrument)," late 14c. In drawing and painting, "work by touches" 1670s.

The sense of "get or go as far as" is from late 14c., hence figuratively "attain equality with" (1838).

As "partake of food," taste, drink (now often in the negative) from late 14c. The sense of "take in hand, receive," especially of money and shading into "get by underhand means" is from 1650s (OED compares French toucher de l'argent, 16c.); as "get or borrow money," by 1760.

With a mixture of senses, of words, etc., "say something that 'hits' " (1520s), and generally, "to sting, nettle, 'get to' " someone, "hurt or wound the mind or feelings," 1580s; hence touch to the quick (c. 1600).

The sense of "affect or move mentally, emotionally, or morally, affect with feeling or emotion" is by mid-14c., with a notion of "touching" the heart or mind.

From c. 1600 as "lay the hand on to cure the king's evil." Also from early 14c. as a euphemism for "have sexual contact with." To touch oneself "masturbate" is by 1927. Touched "deranged" is by 1704 (Shakespeare has "touch'd with madness").

Touch football is attested by 1933 in American English. Touch-typing (1947) was done without looking at the keyboard. To touch one's cap was a symbolic bow or salute.

A toucher (mid-15c.) was often "one who hits the mark," hence a reference to Cupid. To touch off "discharge as a cannon" is by 1884, hence figurative use. To touch bottom, figuratively, is to reach the lowest point.

Proto-Indo-European root meaning "to follow."

It forms all or part of: associate; association; consequence; consequent; dissociate; ensue; execute; extrinsic; intrinsic; obsequious; persecute; persecution; prosecute; pursue; second (adj.) "next after first;" second (n.) "one-sixtieth of a minute;" sect; secundine; segue; sequacious; sequel; sequence; sequester; sociable; social; society; socio-; subsequent; sue; suit; suite; suitor; tocsin.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit sacate "accompanies, follows;" Avestan hacaiti, Greek hepesthai "to follow;" Latin sequi "to follow, come after," secundus "second, the following;" Lithuanian seku, sekti "to follow;" Old Irish sechim "I follow."