sign (n.)

early 13c., "gesture or motion of the hand," especially one meant to communicate something, 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." But 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. Meaning "a mark or device having some special importance" is recorded from late 13c.; that of "a miracle" is from c. 1300. Zodiacal sense in English is from mid-14c. Sense of "characteristic device attached to the front of an inn, shop, etc., to distinguish it from others" is first recorded mid-15c. Meaning "token or signal of some condition" (late 13c.) is behind sign of the times (1520s). In some uses, the word probably is a shortening of ensign. Sign language is recorded from 1847; earlier hand-language (1670s).

sign (v.)

c. 1300, "to make the sign of the cross," from Old French signier "to make a sign (to someone); to mark," from Latin signare "to set a mark upon, mark out, designate; mark with a stamp; distinguish, adorn;" figuratively "to point out, signify, indicate," from signum "identifying mark, sign" (see sign (n.)). Sense of "to mark, stamp" is attested from mid-14c.; that of "to affix one's name" is from late 15c. Meaning "to communicate by hand signs" is recorded from 1700. Related: Signed; signing.

Definitions of sign
sign (n.)
a perceptible indication of something not immediately apparent (as a visible clue that something has happened);
he showed signs of strain
they welcomed the signs of spring
Synonyms: mark
sign (n.)
a public display of a message;
he posted signs in all the shop windows
sign (n.)
any nonverbal action or gesture that encodes a message;
Synonyms: signal / signaling
sign (n.)
structure displaying a board on which advertisements can be posted;
Synonyms: signboard
sign (n.)
(astrology) one of 12 equal areas into which the zodiac is divided;
Synonyms: sign of the zodiac / star sign / mansion / house / planetary house
sign (n.)
(medicine) any objective evidence of the presence of a disorder or disease;
there were no signs of asphyxiation
sign (n.)
having an indicated pole (as the distinction between positive and negative electric charges);
charges of opposite sign
Synonyms: polarity
sign (n.)
an event that is experienced as indicating important things to come;
it was a sign from God
Synonyms: augury / foretoken / preindication
sign (n.)
a gesture that is part of a sign language;
sign (n.)
a fundamental linguistic unit linking a signifier to that which is signified; "The bond between the signifier and the signified is arbitrary"--de Saussure;
sign (n.)
a character indicating a relation between quantities;
don't forget the minus sign
sign (v.)
mark with one's signature; write one's name (on);
She signed the letter and sent it off
Please sign here
Synonyms: subscribe
sign (v.)
approve and express assent, responsibility, or obligation;
Have you signed your contract yet?
Synonyms: ratify
sign (v.)
be engaged by a written agreement;
He signed to play the casino on Dec. 18
The soprano signed to sing the new opera
sign (v.)
engage by written agreement;
They signed two new pitchers for the next season
Synonyms: contract / sign on / sign up
sign (v.)
communicate silently and non-verbally by signals or signs;
He signed his disapproval with a dismissive hand gesture
Synonyms: signal / signalize / signalise
sign (v.)
place signs, as along a road;
sign an intersection
This road has been signed
sign (v.)
communicate in sign language;
I don't know how to sign, so I could not communicate with my deaf cousin
sign (v.)
make the sign of the cross over someone in order to call on God for protection; consecrate;
Synonyms: bless
sign (adj.)
used of the language of the deaf;
Synonyms: gestural / signed / sign-language