Meaning

noun a note that alternates rapidly with another note a semitone above it

noun the articulation of a consonant (especially the consonant `r') with a rapid flutter of the tongue against the palate or uvula

verb pronounce with a trill, of the phoneme `r'

originProbably related to Old English þweran (“to twirl, stir”). Compare twirl, thirl, and Swedish trilla, Norwegian trille, etc.

Etymology from Wiktionary, CC BY-SA 3.0