Definition of: yes

(yes) adverb
As you say; truly; just so: a reply of affirmation or consent: opposed to no, and equivalent to a repetition of the words of a question or command in the form of an assertion. The word is sometimes used to enforce by repetition or addition something that precedes.
—noun plural yes·es or yes·ses A reply in the affirmative.
—v.t. & v.i. yessed, yes·sing To say “yes” (to). [OE gēse, prob. <gēa yea + sī, third person sing. present subj. of bēon be]