Logorrhea
Logorrhea is a disorder of speech. It is a psychological disorder where a person speaks continuously in gibberish or makes no real sense. It is a sign of an underlying mental disorder, and needs psychiatric attention.
Logorrhea happens in many different psychiatric and neurological conditions. Some of these are glossolalia, schizophrenia, bipolar disorder, and schizoaffective disorder.
The term is sometimes used of someone who is just very talkative. This is meant to be a humorous reference.
In popular culture
The dramatic monologue Not I by Samuel Beckett is an example of logorrhea. So is Lucky's speech in the play Waiting for Godot.
In the 1999 E.W. Scripps National Spelling Bee, the spelling bee champion Nupur Lala won with the word logorrhea. Then a documentary, Spellbound was made about the spelling bee.