What does "sonant" mean?

Sonant: (Phonetics) Uttered, as an element of speech, with tone or proper vocal sound, as distinguished from mere breath sound; intonated; voiced; tonic; the opposite of nonvocal, or surd; -- sid of the vowels, semivowels, liquids, and nasals, and particularly of the consonants b, d, g hard, v, etc., as compared with their cognates p, t, k, f, etc., which are called nonvocal, surd, or aspirate. -- n. A sonant letter.