triller

noun

1. A small passerine bird of the genus Lalage belonging to the cuckooshrike family Campephagidae, so called because of the loud trilling calls of the male birds.
2. One who or that which trills.
3. A musical ornament consisting of a rapid alternation between two adjacent notes.

   “When the left hand is the triller, it might seem more difficult to stabilize with the right, which is mostly off the flute.”