Sir

·noun A title prefixed to the Christian name of a knight or a baronet.

II. Sir ·noun A man of social authority and dignity; a lord; a master; a gentleman;

— in this sense usually spelled sire.

III. 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.

IV. 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.