fiduciary
adjective /fɪˈdjuːʃəri/
  /fɪˈduːʃieri/
(law)- involving trust, especially in a situation where a person or company controls money or property belonging to others
- the company’s fiduciary duty to its shareholders
 
Oxford Collocations DictionaryFiduciary is used with these nouns:- duty
 - responsibility
 
Word Originlate 16th cent. (in the sense ‘something inspiring trust; credentials’): from Latin fiduciarius, from fiducia ‘trust’, from fidere ‘to trust’.