"Lord" is a title with various meanings. It can denote a prince or a feudal superior (especially a feudal tenant who holds directly from the king, i.e., a baron). The title today is mostly used in connection with the peerage of the United Kingdom or its constituent countries, although some users of the title do not themselves hold peerages, and use it 'by courtesy'. The title may also be used in conjunction with others to denote a superior holder of an otherwise generic title, in such combinations as "Lord Mayor" or "Lord Chief Justice". The title is primarily taken by men, while women will usually take the title 'lady'. However, this is not universal, as the Lord of Mann and female Lord Mayors are examples of women who are styled 'lord'.

In religious contexts Lord can also refer to various different gods or deities. The earliest uses of Lord in the English language in a religious context were by English Bible translators such as Bede. This reflected the Jewish practice of substituting the spoken Hebrew word 'Adonai' (which means 'My Lord') for YHWH when read aloud.

According to the Oxford Dictionary of English, the etymology of the word can be traced back to the Old English word 'hlāford' which originated from 'hlāfweard' meaning 'bread keeper' or 'loaf-ward', reflecting the Germanic tribal custom of a superior providing food for his followers. Lady, the female equivalent, originates from a similar structure, believed to have originally meant 'loaf-kneader'.

Peerage

Five ranks of peer exist in the United Kingdom, in descending order, these are: duke, marquess, earl, viscount, and baron. The title 'Lord' is used most often by barons who are rarely addressed with any other. The style of this address is 'Lord (X)', for example, Alfred Tennyson, 1st Baron Tennyson, is commonly known as 'Lord Tennyson'. The ranks of marquess, earl and viscounts commonly use lord as well, with viscounts using the same style as used for baron. However, marquesses and earls have a slightly different form of address where they can be called either the 'Marquess/Earl of (X)' or 'Lord (X)'. Dukes also use the style, 'Duke of (X)', but it is not acceptable to refer to them as 'Lord (X)'. Dukes are formally addressed as 'Your Grace', rather than 'My Lord'. In the Peerage of Scotland, the members of the lowest level of the peerage have the title 'Lord of Parliament' rather than baron.

For senior members of the peerage, the title lord also applies by courtesy to some or all of their children; for example the younger sons of dukes and marquesses can use the style 'Lord (first name) (surname)'. The titles are courtesy titles in that the holder does not hold a peerage, and is, according to British law, a commoner.