Fiducial \Fi*du"cial\, a. [L. fiducia trust, confidence; akin to fides faith. See Faith.]

1. Having faith or trust; confident; undoubting; firm. ``Fiducial reliance on the promises of God.'' --Hammond.

2. Having the nature of a trust; fiduciary; as, fiducial power. --Spelman.

Fiducial edge (Astron. & Surv.), the straight edge of the alidade or ruler along which a straight line is to be drawn.

Fiducial line or point (Math. & Physics.), a line or point of reference, as for setting a graduated circle or scale used for measurments.

Source: Webster's Revised Unabridged Dictionary (1913)