fiducial
1. [ adjective ] relating to or of the nature of a legal trust (i.e. the holding of something in trust for another)
Synonyms: fiduciary
Examples:

"a fiduciary contract" "in a fiduciary capacity" "fiducial power"

Related terms: trust trust
2. [ adjective ] used as a fixed standard of reference for comparison or measurement
Examples:

"a fiducial point"

Related terms: physics standard
3. [ adjective ] based on trust
Related terms: trustworthy