Definition of "Sign" :
noun: structure displaying a board on which advertisements can be posted
"The highway was lined with signboards."
noun: a perceptible indication of something not immediately apparent (as a visible clue that something has happened)
"He showed signs of strain."
noun: any nonverbal action or gesture that encodes a message
"Signals from the boat suddenly stopped."
noun: a public display of a message
"He posted signs in all the shop windows."
noun: a character indicating a relation between quantities
"Don't forget the minus sign."
noun: a gesture that is part of a sign language
noun: a fundamental linguistic unit linking a signifier to that which is signified
"The bond between the signifier and the signified is arbitrary."
noun: an event that is experienced as indicating important things to come
"It was a sign from God."
noun: (astrology) one of 12 equal areas into which the zodiac is divided
noun: having an indicated pole (as the distinction between positive and negative electric charges)
"Charges of opposite sign."
noun: (medicine) any objective evidence of the presence of a disorder or disease
"There were no signs of asphyxiation."
verb: make the sign of the cross over someone in order to call on God for protection; consecrate
verb: be engaged by a written agreement
"He signed to play the casino on Dec. 18."
verb: communicate in sign language
"I don't know how to sign, so I could not communicate with my deaf cousin."
verb: mark with one's signature; write one's name (on)
"She signed the letter and sent it off."
verb: communicate silently and non-verbally by signals or signs
"He signed his disapproval with a dismissive hand gesture."
verb: place signs, as along a road
"Sign an intersection."
verb: engage by written agreement
"They signed two new pitchers for the next season."
verb: approve and express assent, responsibility, or obligation
"Have you signed your contract yet?."
adjective: used of the language of the deaf