something that is communicated by or to or between people or groups

be a signal for or a symptom of

make conspicuous or noteworthy

point out carefully and clearly

communicate silently and non-verbally by signals or signs

communicate silently and non-verbally by signals or signs

a signal that encodes something (e.g., picture or sound) that has been recorded

the number is used in calling a particular telephone

a signal to begin (as in a race)

a signal announcing the approach of a storm (particularly a storm of marked violence)

a signal transmitted along a narrow path; guides airplane pilots in darkness or bad weather