The Reverend is an honorific style given before the names of certain Christian clergy and ministers. There are sometimes differences in the way the style is used in different countries and church traditions. The Reverend is correctly called a style, but is sometimes referred to as a title, form of address, or title of respect. The style is also sometimes used by leaders in other religions such as Judaism and Buddhism.
The term is an anglicisation of the Latin reverendus, the style originally used in Latin documents in medieval Europe. It is the gerundive or future passive participle of the verb revereri ("to respect; to revere"), meaning "[one who is] to be revered/must be respected". The Reverend is therefore equivalent to The Honourable or The Venerable. It is paired with a modifier or noun for some offices in some religious traditions: Lutheran archbishops, Anglican archbishops, and most Catholic bishops are usually styled The Most Reverend (reverendissimus); other Lutheran bishops, Anglican bishops, and Catholic bishops are styled The Right Reverend.
With Christian clergy, the forms His Reverence and Her Reverence are also sometimes used, along with their parallel in direct address, Your Reverence. The abbreviation HR is sometimes used.
In traditional and formal English usage it is still considered incorrect to drop the definite article, the, before Reverend. In practice, however, the is often not used in both written and spoken English. When the style is used within a sentence, the is correctly in lower-case. The usual abbreviations for Reverend are Rev., Revd and Rev'd.
The Reverend is traditionally used as an adjectival form with first names (or initials) and surname (e.g. The Reverend John Smith or The Reverend J. F. Smith); The Reverend Father Smith or The Reverend Mr Smith are correct though now old-fashioned uses. Use of the prefix with the surname alone (The Reverend Smith) is considered a solecism in traditional usage: it would be as irregular as calling the person in question "The Well-Respected Smith".