A vocal, or sometimes a whispered, sound modified by resonance in the oral passage, the peculiar resonance in each case giving to each several vowel its distinctive character or quality as a sound of speech; -- distinguished from a consonant in that the latter, whether made with or without vocality, derives its character in every case from some kind of obstructive action by the mouth organs. Also, a letter or character which represents such a sound. See Guide to Pronunciation, // 5, 146-149.
My favorite rhymes are sort of half-rhymes where you might just get the vowel sound the same, but it's not really a true rhyme. That gives you far more flexibility to capture the feeling you're trying to express. But sometimes it's best not to have any rhyme. Conor Oberst
'Y' is about the weakest letter of all. 'Y' can't make up its mind if it's a vowel or a consonant, can it? David Mitchell