logorrhea

n. excessive talkativeness (symptom of certain mental disorders); prolixity, verbosity, excessive wordiness

Logorrhoea or logorrhea (Greek λογορροια, logorrhoia, “word-flux”) is defined as an “excessive flow of words” and, when used medically, refers to incoherent talkativeness that occurs in certain kinds of mental illness, such as mania. The spoken form of logorrhoea (in the non-medical sense) is a kind of that uses superfluous or fancy words to disguise a useless or simple message as useful or intellectual, and is commonly known as “verbal diarrhea” or “diarrhea of the mouth.”
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Logorrhea /log·or·rhea/ pressured speech; excessive and rapid speech, seen in certain mental disorders. log·or·rhe·a n. Excessive use of words. [more]Logorrhea - Community and Resources

Noun
1. pathologically excessive (and often incoherent) talking
(synonym) logomania
(hypernym) mania, passion, cacoethes

Excessive talking (or verbal diarrhea)