A speech sound intermediate between a vowel and a consonant, e.g. w or y.
- ‘The play opens with a speech by Flavius (spelled ‘Flauius’ in the old Latin style where u and v are not distinguished since the latter is just the semivowel corresponding to the vowel represented by the former).’
- ‘Parts are numbered from one to six, but the second is missing (just as the second vowel is missing among the vowels and the semivowel Y).’
Mid 16th century: from semi- + vowel, on the pattern of Latin semivocalis.