(a) Certainly, truly;—often used parenthetically with reduced semantic force;
(b) in collocation with nai: affirmatively, thus, so; ye than nai, nai than ye.
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(a) As an affirmative reply to a direct or an indirect question: yes; seien ye
(b) as an affirmation of the truth or correctness of an assertion, a proposition, etc.: that is right, it is so, yes;……