A relationship or relation (to something).

A measurement one can compare to.

Information about a person, provided by someone (a referee) with whom they are well acquainted.

To provide a list of references for (a text).

“You must thoroughly reference your paper before submitting it.”

To refer to, to use as a reference.

“Reference the dictionary for word meanings.”

To mention, to cite.

“In his speech, the candidate obliquely referenced the past failures of his opponent.”