fi·du·cial 
(fĭ-dshəl, -dy-, fī-)
(fĭ-dshəl, -dy-, fī-)adj.
1. Based on or relating to faith or trust.
2. Relating to or characteristic of a legal trust; fiduciary.
3. Regarded or employed as a standard of reference, as in surveying.
[Late Latin fīdūciālis, from Latin fīdūcia, trust, from fīdere, to trust; see bheidh- in the Appendix of Indo-European roots.]
fi·ducial·ly adv.