(sometimes also used uncountably) A visible indication.
I gave them a thumbs-up sign.
Physical evidence left by an animal.
The hunters found deer sign at the end of the trail.
A clearly visible object, generally flat, bearing a short message in words or pictures.
I missed the sign at the corner so I took the wrong turn.
A wonder; miracle; prodigy.
An astrological sign.
Your sign is Taurus? That's no surprise.
Positive or negative polarity, as denoted by the + or - sign.
I got the magnitude right, but the sign was wrong.
A specific gesture or motion used to communicate by those with speaking or hearing difficulties; now specifically, a linguistic unit in sign language equivalent to word in spoken languages.
Sign language in general.
Sorry, I don't know sign very well.
An omen.
"It's a sign of the end of the world," the doom prophet said.
A property of the body that indicates a disease and, unlike a symptom, is unlikely to be noticed by the patient.
A military emblem carried on a banner or standard.
To make a mark
To make the sign of the cross
To indicate