Meaning of “sign” - Learner’s Dictionary

sign

noun [ C ] uk us /saɪn/
PROOF

B1 something that shows that something is happening:

Flowers are the first sign of Spring.
[ + (that) ] It's a sign that things are improving.
Staff are showing signs of strain.
NOTICE

A2 a symbol or message in a public place that gives information or instructions:

a road sign
a 'no-smoking' sign
SYMBOL

B2 a symbol that has a particular meaning:

a dollar/pound sign
the sign of the cross
MOVEMENT

B1 a movement you make to give someone information or tell them what to do

→ See also star sign

(Definition of “sign noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)