noun a title prefixed to the christian name of a knight or a baronet.
2. sir ·noun a man of social authority and dignity; a lord; a master; a gentleman;
in this sense usually spelled sire.
3. sir ·noun an english rendering of the latin dominus, the academical title of a bachelor of arts;
formerly colloquially, and sometimes contemptuously, applied to the clergy.
4. sir ·noun a respectful title, used in addressing a man, without being prefixed to his name;
used especially in speaking to elders or superiors; sometimes, also, used in the way of emphatic formality.