anything that gives a reason for believing, that makes clear or proves, something

proof

something that points to or indicates; pointer (on an instrument) showing measurements; an alphabetical list of names, subjects etc at the end of a book or no cards (a card index) in a library etc

indication

evidence, clue

evidence, clue

of index

indication

a change in the body's condition that is a sign (of illness); a sign of the existence (of something)

sign of illness or problem

small; a sign, evidence or mark

indication, remembrance