trill

Etymology 1

From Middle English trillen, from Italian trillo, trillare. Compare Norwegian trille, Swedish trilla.

noun

1. (music) A rapid alternation between an indicated note and the one above it as an ornament; in musical notation usually indicated with the letters tr written above the staff.
2. (phonetics) A type of consonantal sound that is produced by vibrations of the tongue against the place of articulation: for example, Spanish ⟨rr⟩, /r/.
3. A tremulous high-pitched vocal sound produced by cats.

verb

1. (intransitive) To create a trill sound; to utter trills or a trill; to play or sing in tremulous vibrations of sound; to have a trembling sound; to quaver.
   To judge of trilling notes and tripping feet. 1692, John Dryden, Cleomenes, the Spartan Hero, a Tragedy
2. (transitive) To impart the quality of a trill to; to utter as, or with, a trill.
   to trill a note, or the letter r

Etymology 2

Perhaps identical to Etymology 3, but compare the same sense of drill, and German trillen, drillen.

verb

1. (intransitive, obsolete) To trickle.
   Whisper'd sounds / Of waters, trilling from the riven stone.

Etymology 3

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

verb

1. (intransitive, obsolete) To twirl.

Etymology 4

Perhaps a blend of true + real.

adj

1. (slang, hip-hop culture) True, respected.
   All my trill niggas know who be bringin da funk / Lees and shell toes like it's Black History Month 2007, “Black History Month”, in The Inevitable Rise and Liberation of NiggyTardust!, performed by Saul Williams
   LAMAR: Oh, really? That's a nice change from fools comin' up on us. / FRANKLIN: That's trill, homie. / LAMAR: You damn straight that's trill, partner, but it's a shame I don't believe it. You wanna drop some notes on that shit, I'll give you the odds, homie. 2013, Grand Theft Auto V, Rockstar Games, level/area: Repossession
   Middle finger to the critics, me and my nigga Skrillex / You know we finna kill it, A$AP we the trillest 2013, “Wild for the Night”, performed by A$AP Rocky