sirrah

title of honor of a knight or baronet (until 17c. also a title of priests), c. 1300, a variant of sire (q.v.) that was used originally only in unstressed position. It is not an acronym of anything.

It was generalized as a respectful form of address by mid-14c., and eventually extended to all equals or used without regard for rank. It has been used as a salutation at the beginning of letters from early 15c. As a noun, "person of rank or importance," from 14c.

1836, representing a quick reply of yes, sir, which is attested by 1799 and in 19c. writing was a typical phrase for restaurant waiters taking orders. Extended form yessiree is attested from 1846 (in U.S., siree for sir is attested from 1823).