The modern plural form is Misters[citation needed], although its usual formal abbreviation Messrs(.
[2][5] Messieurs is the plural of monsieur (originally mon sieur, "my lord"), formed by declining both of its constituent parts separately.
[5] Historically, mister was applied only to those above one's own status if they had no higher title such as Sir or my lord in the English class system.
That understanding is now obsolete, as it was gradually expanded as a mark of respect to those of equal status and then to all men without a higher style.
Today, on correspondence from Buckingham Palace, a man who is a UK citizen is addressed with post-nominal "Esq.
In other circumstances, similar usage to indicate respect combined with familiarity is common in most anglophone cultures, including that of the southern United States.
In the United Kingdom, Ireland and in some Commonwealth countries (such as South Africa, New Zealand and some states of Australia), many surgeons use the title Mr (or Miss, Ms, Mrs, as appropriate), rather than Dr (Doctor).
Among Catholic clergy, "Mr" is the correct honorific and form of address for seminarians and other students for the priesthood.
Orders founded before the 16th century do not, as a rule, follow this practice: a Franciscan or Dominican, for instance, becomes a friar after novitiate and so is properly titled "Brother" or, if a priest, "Father".