Sir (Edmund) Richard Vere Lacon, 9th Baronet

''Sir'' is a formal honorific address in English for men, derived from Sire in the High Middle Ages. Both are derived from the old French "Sieur" (Lord), brought to England by the French-speaking Normans, and which now exist in French only as part of "Monsieur", with the equivalent "My Lord" in English. Traditionally, as governed by law and custom, Sir is used for men titled as knights, often as members of orders of chivalry, as well as later applied to baronets and other offices. As the female equivalent for knighthood is damehood, the female equivalent term is typically Dame. The wife of a knight or baronet tends to be addressed as Lady, although a few exceptions and interchanges of these uses exist.

Additionally, since the late modern period, Sir has been used as a respectful way to address a man of superior social status or military rank. Equivalent terms of address for women are Madam (shortened to Ma'am), in addition to social honorifics such as Mrs, Ms or Miss.

Etymology

''Sir'' derives from the honorific title ''sire''; ''sire'' developed alongside the word ''seigneur'', also used to refer to a feudal lord. Both derived from the Vulgar Latin , ''sire'' comes from the nominative case declension and ''seigneur'', the accusative case declension .

The form 'Sir' is first documented in English in 1297, as the title of honour of a knight, and latterly a baronet, being a variant of ''sire'', which was already used in English since at least c.1205 (after 139 years of Norman rule) as a title placed before a name and denoting knighthood, and to address the (male) Sovereign since c.1225, with additional general senses of 'father, male parent' is from c.1250, and 'important elderly man' from 1362.

Entitlement to formal honorific address by region

Commonwealth of Nations

The prefix is used with the holder's given name or full name, but never with the surname alone. For example, whilst Sir Alexander and Sir Alexander Fleming would be correct, Sir Fleming would not.

Today, in the UK and in certain Commonwealth realms, a number of men are entitled to the prefix of 'Sir', including knights bachelor, knights of the orders of chivalry and baronets; although foreign nationals can be awarded honorary knighthoods. Honorary knights do not bear the prefix "Sir" nor do they receive an accolade; instead they use the associated post-nominal letters.

Church of England clergy who receive knighthoods do also not receive an accolade and therefore do not use the title 'Sir', but instead refer to their knighthood using post-nominal letters. For example, the Reverend John Polkinghorne, KBE would never be referred to as ''Sir John Polkinghorne''. Clergy of other denominations may use different conventions.

Only citizens of Commonwealth realms may receive substantive knighthoods and have the privilege of the accompanying style. In general, only knighthoods in dynastic orders – those orders in the personal gift of the Sovereign and Head of the Commonwealth (the Order of the Garter, the Order of the Thistle and the knighthoods in the Royal Victorian Order) – are recognised across the Commonwealth realms, along with their accompanying styles.

British knighthoods (in the Orders of the Bath, St. Michael and St. George, and in the Order of the British Empire, along with Knights Bachelor) were known as ''imperial honours'' during the existence of the British Empire. Those honours continued to be conferred as substantive, not honorary, awards by most Commonwealth realms into the 1990s. Since then, though former imperial honours are still awarded by certain Commonwealth realms, many of them have discontinued grants of British honours as they have developed their own honours systems, some of which include knighthoods. Today, British honours are only substantive for British nationals so recognised, including dual nationals, and for nationals of those realms which have retained them as part of their honours systems.

Dual national