I. noun
1.
a motion, action, gesture, or word by which a command, thought, or wish is expressed
put a finger to her lips as a sign to keep quiet
Synonyms: high sign, signal
Related Word: gesticulation, gesture, motion; hint, indication, suggestion, warning
2.
Synonyms: character 1, mark, symbol
3.
Synonyms: expression 3, gesture, indication, reminder, token
Related Word: symbolization; attestation, evidence, proof
4.
Synonyms: indication 3, evidence, index, indicia, mark, significant, symptom, token
Related Word: earmark, exponent, indicator; exhibit, show
II. verb
1.
to affix a signature to
he refused to sign a confession
Synonyms: autograph, ink, signature, subscribe
Idioms: put one's John Hancock on, put one's John Henry down ( or on)
2.
Synonyms: signal , flag, gesture, motion, signalize