fi·du·cial \fə̇ˈd(y)üshəl, fīˈ-\adjective Etymology: Late Latin fiducialis, from Latin fiducia + -alis -al 1.: founded on faith or trust < his fiducial reliance on certain religious beliefs > 2.: having the nature of a trust : fiduciary < a fiducial power > 3.: taken as an origin or zero of reference < a fiducial point on a scale > • fi·du·cial·ly\-əlē\adverb