PHTHONGAL a. 2 definitions
Formed into, or characterized by, voice; vocalized; -- said of all the vowels and the semivowels, also of the vocal or sonant consonants g, d, b, l, r, v, z, etc.
R n.
R, the eighteenth letter of the English alphabet, is a vocal consonant. It is sometimes called a semivowel, and a liquid. See Guide to Pronunciation, §§ 178, 179, and 250-254. "R is the dog's letter and hurreth in the sound." B. Jonson.