/
fɪˈdjuːʃ(ə)ri/
adj.
  - Law  involving trust, especially with regard to the relationship between a trustee and a beneficiary.
- Finance  (of a paper currency) depending for its value on securities or the reputation of the issuer.
n.
 (pl. fiduciaries)
 a trustee.
Etymology
C16 (in the sense ‘credentials’): from L. fiduciarius, from fiducia ‘trust’.