vocal vs vowel

vocal

noun
  • A vocal sound; specifically, a purely vocal element of speech, unmodified except by resonance; a vowel or a diphthong; a tonic element; a tonic. 

  • A part of a piece of music that is sung. 

  • A musical performance involving singing. 

  • A man in the Roman Catholic Church who has a right to vote in certain elections. 

adj
  • Relating to, composed or arranged for, or sung by the human voice. 

  • Of, pertaining to, or resembling the human voice or speech. 

  • Consisting of, or characterized by, voice, or tone produced in the larynx, which may be modified, either by resonance, as in the case of the vowels, or by obstructive action, as in certain consonants, such as v, l, etc., or by both, as in the nasals m, n, ng. 

  • Used in the production of speech sounds. 

  • Synonym of expressive. 

  • Uttered or modulated by the voice; expressed in words. 

  • Full of voices. 

  • Expressing opinions or feelings freely, loudly, or insistently. 

  • Having or exercising the power of producing voice, speech, or sound. 

  • Synonym of vocalic. 

vowel

noun
  • A sound produced by the vocal cords with relatively little restriction of the oral cavity, forming the prominent sound of a syllable. 

  • A letter representing the sound of vowel; in English, the vowels are a, e, i, o, u, and y. 

verb
  • To add vowel points to a consonantal script (e.g. niqqud in Hebrew or harakat in Arabic). 

How often have the words vocal and vowel occurred in a corpus of books? (source: Google Ngram Viewer )