A signal; anything that indicates, or is characteristic of, the presence of something else, especially of something undesirable.
A perceived change in some function, sensation or appearance of a person that indicates a disease or disorder, such as fever, headache or rash; strictly, a symptom is felt or experienced by the patient, while a sign can be detected by an observer.
A faint mark or visible sign left by something which is lost, or has perished, or is no longer present.
A mark left on the earth by a foot.
A vestigial organ; a non-functional organ or body part that was once functional in an evolutionary ancestor.