An esquire (abbreviated Esq.) is a person of a certain social status; always rather vague in its extent, the term has become practically meaningless today. Nonetheless, its use as a postnominal honorific remains fairly common.

The term is British in origin. Ultimately deriving from the mediaeval squires who assisted knights, the term came to be used automatically by men of gentle birth. Thus use of the word postnominally represented nothing more than the claim to be a gentleman. More specifically, though, a distinction was made between men of the upper and lower gentry, who were "esquires" and "gentlemen" respectively (between, for example, "Thomas Smith, Esq." and "William Jones, Gent."). A late example of this distinction is in the list of subscribers to The History of Elton, by the Rev. Rose Fuller Whistler, published in 1882, which clearly distinguishes between subscribers designated "Mr" (another way of indicating gentlemen) and those allowed "Esquire." (source: wikipedia)