fiducial

From Late Latin fīdūciālis, from fīdūcia (“trust, reliance”) + -ālis, from fīdō (“I trust”).

IPA^(key): /fɪˈduːʃəl/

fiducial (comparative more fiducial, superlative most fiducial)

1. Accepted as a fixed basis of reference.

   Rulers and coins make good fiducial markers in photographs.

2. Based on having trust.

Do not confuse fiducial with fiduciary, notwithstanding that the words are cognate, based on a root of trust and reference to authoritative standards.

fiducial (plural fiducials)

1. In photography, a familiar reference object used to show size or scale, such as a ruler or a coin; a fiducial marker.
2. In manufacturing, a small mark on a circuit board used to align components; a fiducial point.

   Coordinate term: registration mark (in printing)