bona fides
/ˌbəʊnəˈfaɪdiːz/noun
mass noun
1- a person's honesty and sincerity of intention真诚, 诚意：
he went to great lengths to establish his liberal bona fides.
他不遗余力使人接受他慷慨的诚意。
1.1
- treated as pl. informal documentary evidence showing that a person is what they claim to be; credentials〈非正式〉介绍信, 证书; 信任状, 国书。
词源
Latin, literally 'good faith'.