a vowel-like sound that acts like a consonant, in that it serves the same function in a syllable carrying the same amount of prominence as a consonant relative to a true vowel, the nucleus of the syllable. In English and many other languages the chief semivowels are (w) in well and (j), represented as y, in yell
2.
a frictionless continuant classified as one of the liquids; (l) or (r)
Also called (US and Canadian): glide
semivowel in American English
(ˈsɛmɪˌvaʊəl)
noun Phonetics
a vowel-like sound occurring in consonantal positions in the same syllable with a true vowel, characterized by brief duration and rapid change from one position of articulation to another