sign

1. a token or indication; a piece of evidence:

   The smoke curling from the chimney was a sign that someone was in the cabin.

   Synonyms: signal, suggestion, hint, trace

2. any object, action, event, pattern, etc., that is taken as conveying a meaning:

   I took her silence and fidgeting as a sign of disagreement.

   Rising sales of disaster survival kits are a sign of the times.

3. a conventional or arbitrary mark, figure, or symbol used as an abbreviation for the word or words it represents.
4. a motion or gesture used to express or convey an idea, command, decision, etc.:

   Her nod was a sign that it was time to leave.

   Synonyms: signal

5. a notice, bearing a name, direction, warning, or advertisement, that is displayed or posted for public view:

   a traffic sign;

   a store sign.

6. a trace; vestige:

   There wasn't a sign of them.

7. an arbitrary or conventional symbol used in musical notation to indicate tonality, tempo, etc.
8. Medicine/Medical. the objective indications of a disease.
9. any meaningful gestural unit belonging to a sign language.
10. an omen; portent:

    The general unrest was a sign of the approaching revolution.

    Synonyms: augury, hint, indication

11. sign of the zodiac.
12. sign language ( def 1 ).
13. Usually signs. traces, such as footprints or scat, of a wild animal.
14. Mathematics.
    1. a plus sign or minus sign used as a symbol for indicating addition or subtraction.
    2. a plus sign or minus sign used as a symbol for indicating the positive or negative value of a quantity, as an integer.
    3. multiplication sign.
    4. division sign.
    5. a symbol, as  or !, used to indicate a radical or factorial operation.

1. to affix a signature to:

   to sign a letter.

2. to write as a signature:

   to sign one's name.

3. to engage by written agreement:

   to sign a new player.

4. to mark with a sign, especially the sign of the cross.
5. to communicate by means of a sign; signal:

   He signed his wish to leave.

6. to convey (a message) in a sign language.
7. Obsolete. to direct or appoint by a sign.

1. to write one's signature, as a token of agreement, obligation, receipt, etc.:

   to sign for a package.

2. to make a sign or signal:

   He signed to her to go away.

3. to employ a sign language for communication.
4. to obligate oneself by signature:

   He signed with another team for the next season.

verb phrase

1. to enlist, as in an organization or group; to register or subscribe:

   to sign up for the navy;

   to sign up for class.

2. to assign or dispose of by affixing one's signature to a document:

   She signed over her fortune to the church.

3. to record or authorize one's arrival (or departure) by signing a register. Also sign out.
4. 1. to employ; hire.
   2. to bind oneself to work, as by signing a contract:

      He signed on as a pitcher with a major-league team.

   3. to start radio or television broadcasting, especially at the beginning of the day.
   4. Computers. log ¹( def 18a ).
5. 1. to withdraw, as from some responsibility or connection.
   2. to cease radio or television broadcasting, especially at the end of the day.
   3. Informal. to become silent:

      He had exhausted conversation topics and signed off.

   4. to indicate one's approval explicitly if not formally:

      The president is expected to sign off on the new agreement.