noun.
Something, such as a typographical device, that serves to indicate.
The Century Dictionary and Cyclopedia
Serving to indicate, point out, or suggest.
noun.
That which serves to point out or indicate; specifically, in medicine, that which indicates a suitable remedy or treatment, as a symptom or combination of symptoms, or the history of the case.
the GNU version of the Collaborative International Dictionary of English
noun.
That which indicates or points out.
adjective.
Serving to point out, as a remedy; indicating.