From: Greg F. - PM
Date: 30 Oct 17 - 09:40 AM
For your information, Professor:

ev?i?dence
ˈevədəns/
noun
noun: evidence
1.the available body of facts or information indicating whether a belief or proposition is true or valid.

Yes, that is one meaning of the word, which specifies it as "the body of facts".
But it can also refer to individual facts, or individual testimonies:
Law Information drawn from personal testimony, a document, or a material object, used to establish facts in a legal investigation or admissible as testimony in a law court.
'without evidence, they can't bring a charge'
From Oxford dictionaries
So 'witness testimony' is 'evidence' despite what others may have told you.