If a bird trills, it sings with short, high-pitched, repeated notes.
At one point a bird trilled in the Conservatory. [VERB]
2. verb
If you say that a woman trills, you mean that she talks or laughs in a high-pitched voice which sounds rather musical but which also sounds rather irritating.
'How adorable!' she trills. [VERB with quote]
3. countable noun
A trill is the playing of two musical notes repeatedly and quickly one after the other. [technical]