warble

(noun) a lumpy abscess under the hide of domestic mammals caused by larvae of a botfly or warble fly.

(verb) sing or play with trills, alternating with the half note above or below. Synonyms: trill, quaver.

(verb) sing by changing register; sing by yodeling. Synonyms: yodel, descant. Example: "The austrians were yodeling in the mountains."