conviction

确信，信服，深信英释nnthe feeling of being sure about something and having no doubts

1 It was a reasonable explanation, but his voice lacked conviction ..这解释合情合理，只是他的语气不坚定。

2 It took her so much effort to speak that what she said carried great conviction (= showed she felt sure of what she said ) ..她费了很大的劲在说，因此说出来的话显得很确定。