jargon

a characteristic language of a particular group (as among thieves)

Confused, unintelligible language; gibberish; hence, an artificial idiom or dialect; cant language; slang.

from Greek 'gargos' meaning 'garish, colorful'

“Sentiments we won't discuss; though you know that sentiments have a bearing on social life: are factors, as they say in their later jargon.”

— George Meredith, Complete Project Gutenberg Works of George Meredith

“Progressive Jargon Aphasia is a fluent or receptive aphasia in which the person's speech is incomprehensible, but appears to make sense to them.”