Sir is an honorific address used as a courtesy title to address a man without using his given or family name in many English speaking cultures. It is often used in formal correspondence (Dear Sir, Right Reverend Sir).

The term is often reserved for use only towards one of superior rank or status, such as an educator or commanding officer, an elder (especially by a minor), or as a form of address from a merchant to a customer.

Equivalent terms of address are "ma'am" or "madam" in most cases, or in the case of a very young woman, girl, or unmarried woman who prefers to be addressed as such, "miss". The equivalent term for a knighted woman is Dame, or "Lady" for the wife of a knight.

Sir derives from the Middle French honorific title sire (messire gave rise to mylord), from the Old French sieur (itself a contraction of Seigneur meaning 'lord'), from the Latin adjective senior (elder), which yielded titles of respect in many European languages. The form sir is first documented in English in 1297, as title of honor of a knight or baronet, being a variant of sire, which was already used in English since at least c.1205 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.

A tor is a large, free-standing residual mass (rock outcrop) that rises abruptly from the surrounding smooth and gentle slopes of a rounded hill summit or ridge crest. In the South West of England, where the term originated, it is also a word used for the hills themselves – particularly the high points of Dartmoor in Devon and Bodmin Moor in Cornwall.

The word tor (Cornish tor, Old Welsh twrr, Modern Welsh tŵr, Scots Gaelic tòrr), meaning hill, is notable for being one of the very few Celtic loanwords to be borrowed into vernacular English before the modern era – such borrowings are mainly words of a geographic or topographical nature. Similar words include crag (from the Welsh word craig, meaning "rock") and avon (from the Welsh word afon, meaning "river").

Tors are usually composed of granite or metamorphic rocks, but they can also develop in volcanic rocks and occasionally other hard rocks such as quartzite. They are the result of millions of years of weathering.

For example the Dartmoor granite was emplaced around 280 million years ago and as it cooled it contracted leaving a multitude of mainly vertical cracks; these facilitated hydrothermal circulation which both chemically altered the rock surrounding the cracks and deposited minerals in them. The rocks that overlaid the granite pluton were eroded quickly (in geological terms) and the consequent release of pressure caused the formation of sub-horizontal joints which tended to follow the shape of the land and which started the separation of the upper part of the pluton into blocks of varying sizes.