Trill

In music, a trill is an ornament which consists of rapid alternation of two adjacent notes, and is thus an example of a slow frequency modulation or vibrato. Before the middle of the seventeenth century it was called a tremolo, and later a shake.

In phonetics, a trill is a type of articulation in which the air current from the larynx is used to make one of the articulators vibrate rapidly. There are no good examples in English but the trilled 'r' is common in European languages. See: Consonant.