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