Definition of sign:
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"
a public display of a message; "he posted signs in all the shop windows"
any nonverbal action or gesture that encodes a message; "signals from the boat suddenly stopped"
structure displaying a board on which advertisements can be posted; "the highway was lined with signboards"
(astrology) one of 12 equal areas into which the zodiac is divided
(medicine) any objective evidence of the presence of a disorder or disease; "there were no signs of asphyxiation"
having an indicated pole (as the distinction between positive and negative electric charges); "he got the polarity of the battery reversed"; "charges of opposite sign"
an event that is experienced as indicating important things to come; "he hoped it was an augury"; "it was a sign from God"
a gesture that is part of a sign language
a fundamental linguistic unit linking a signifier to that which is signified; "The bond between the signifier and the signified is arbitrary"--de Saussure
a character indicating a relation between quantities; "don't forget the minus sign"
mark with one's signature; write one's name (on); "She signed the letter and sent it off"; "Please sign here"
approve and express assent, responsibility, or obligation; "All parties ratified the peace treaty"; "Have you signed your contract yet?"
be engaged by a written agreement; "He signed to play the casino on Dec. 18"; "The soprano signed to sing the new opera"
engage by written agreement; "They signed two new pitchers for the next season"
communicate silently and non-verbally by signals or signs; "He signed his disapproval with a dismissive hand gesture"; "The diner signaled the waiters to bring the menu"
place signs, as along a road; "sign an intersection"; "This road has been signed"
communicate in sign language; "I don't know how to sign, so I could not communicate with my deaf cousin"
make the sign of the cross over someone in order to call on God for protection; consecrate
used of the language of the deaf