Open English Wordnet
Nouns
(n)trill, shakea note that alternates rapidly with another note a semitone above it (n)trillthe articulation of a consonant (especially the consonant ‘r’) with a rapid flutter of the tongue against the palate or uvula“he pronounced his R's with a distinct trill” Verbs
(v)trillpronounce with a trill, of the phoneme /r/“Some speakers trill their r's” (v)warble, trill, quaversing or play with trills, alternating with the half note above or below