yes: [OE] Yes is descended from Old English gese. It is thought that this was a compound formed from gēa ‘yes’ (ancestor of archaic English yea and related to German and Dutch ja ‘yes’) and sīe, the third-person present singular subjunctive of be, and that it therefore originally meant literally ‘yes, may it be so’. It was at first used as a response to negative questions, while yea was used for positive questions, but around the end of the 16th century this distinction began to disappear, and yea has since died out. => yea
