Senhor n : a Portuguese title of respect; equivalent to English `Mr'
Senhor (abbreviation: Sr.; plural: Senhores, abbreviation: Srs.), from the Latin Senior (comparative of Senex, "old man"), is the Portuguese word for Lord, Sir or Mister. Its feminine form is Senhora (plural Senhoras, abbreviation: Sras.). Its Spanish equivalent is Señor.
Originally it was only used to designate a feudal Lord or Sire, as well as being one of the names of God.
With time its usage spread and, as means of differentiation, noble people began to use Senhor Dom (as when referring to the kings or members of the high noblity), which translates literally in English as "Lord Lord".
Presently it is used in the same context as Mister (Senhor Silva meaning Mr. Silva), or as a way of saying a formal "You" ("O senhor tem uma casa" meaning "You (male) have a house"). In formal contexts o senhor, a senhora, os senhores and as senhoras (masculine singular, feminine singular, masculine plural, and feminine plural "you", respectively) are preferred. However, there is considerable regional variation in the use of these terms, and more specific forms of address are sometimes employed. O senhor / a senhora are the most ceremonious forms of address. English speakers may find the latter construction akin to the parliamentary convention of referring to fellow legislators in the third person (as "my colleague", "the gentleman", "the member", etc.), although the level of formality conveyed by o senhor is not as great. In fact, variants of o senhor and a senhora with more nuanced meanings such as o professor ("professor"), o colega ("colleague") and o pai ("father") are also employed as personal pronouns. Often Senhor is followed by another title or job description, such as Doctor (Senhor Doutor), Engineer (Senhor Engenheiro), Teacher or Professor (Senhor Professor), or Police officer (Senhor Polícia), thus conveying a high level of formality.
Tradicionally, but not presently, the feminine form Senhora was only used for a married woman (a single woman was addressed formally as Menina, "young girl", or by the diminutive Senhorita, "little lady").