Trill (vocalization)

A trill was a vocalization made by various animals. It was a vibratory and quavering sound.

In 3188, the trance worm Molly trilled after approaching Cleveland Booker, who responded by touching her lowered head with his right hand. (DIS: "That Hope Is You, Part 1")

The closed captioning for the episode identified this vocalization.
In animals, such as cats, trilling was "seen as a sign of their comfort, ease, and trust" in an individual. [1]

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