R, or r, is the eighteenth letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ar (pronounced /ˈɑːr/), plural ars,[1] or in Ireland or /ˈɔːr/.[2]
The letter ⟨r⟩ is the eighth most common letter in English and the fourth-most common consonant, after ⟨t⟩, ⟨n⟩, and ⟨s⟩.[3]
The name of the letter in Latin was er (/ɛr/), following the pattern of other letters representing continuants, such as ⟨F⟩, ⟨L⟩, ⟨M⟩, ⟨N⟩, and ⟨S⟩. This name is preserved in French and many other languages. In Middle English, the name of the letter changed from /ɛr/ to /ar/, following a pattern exhibited in many other words such as farm (compare French ferme) and star (compare German Stern).
The letter R is sometimes referred to as the littera canīna 'canine letter', often rendered in English as the dog's letter. This Latin term referred to the Latin ⟨R⟩ that was trilled to sound like a growling dog, a spoken style referred to as vōx canīna 'dog voice' (e.g. in Spanish perro 'dog').[7]
In Romeo and Juliet, such a reference is made by Juliet's nurse in Act 2, scene 4, when she calls the letter R "the dog's name". The reference is also found in Ben Jonson's English Grammar.[8]
The letter ⟨R⟩ is believed to derive ultimately from an image of a head, used in Semitic alphabets for the sound /r/ because the word for 'head' was rêš or similar in most Semitic languages. The word became the name of the letter, as an example of acrophony.