Semivowels, also known as glides or non-syllabic vowels, are vowels that form diphthongs with full syllabic vowels. That's, they're vowel-like sounds that don't form the nucleus of a syllable or mora; they aren't the most prominent part of the syllable. They're normally written by adding the IPA non-syllabicity mark [ ̯ ] to a vowel letter, but often for simplicity the vowel letter alone's written. Semivowels may contrast with approximants, which are similar to but closer than vowels or s… (More on Semivowel)