(used to express affirmation or assent or to mark the addition of something emphasizing and amplifying a previous statement): Do you want that? Yes, I do.
2.
(used to express an emphatic contradiction of a previously negative statement or command): Don't do that! Oh, yes I will!
3.
(used, usually interrogatively, to express hesitation, uncertainty, curiosity, etc.): “Yes?” he said as he opened the door. That was a marvelous show! Yes?
4.
(used to express polite or minimal interest or attention.)
to give an affirmative reply to; give assent or approval to.
interjection
7.
(used as a strong expression of joy, pleasure, or approval.)
Origin: before 900;Middle Englishyes, yis,Old Englishgēse (adv. and noun), probably equivalent to gēayea + sī be it (present subjunctive singular of bēon to be)
O.E. gise, gese "so be it!," probably from gea, ge "so" (see yea) + si "be it!," third pers. imperative of beon "to be" (see be). Originally stronger than simple yea. Used in Shakespeare mainly as an answer to negative questions. Yes-man is first recorded 1912, Amer.Eng.