General:
* Nonsense
* Gibberish
* Blabbermouth
* Blarney
* Balderdash
* Fiddle-faddle
* Hogwash
* Rot
* Drivel
* Trash talk
* Rambling
More specific:
* Babble (incoherent speech, usually of a child)
* Mumbo jumbo (meaningless ritualistic language)
* Doubletalk (deceptive or evasive language)
* Goofy talk (silly or nonsensical speech)
* Waffle (vague or evasive talk)
Informal:
* B.S. (abbreviation for "bullshit")
* Hot air
* Crap
* Rubbish
* Stuff and nonsense
The best term to use will depend on the specific situation. For example, "gibberish" might be a good choice for describing unintelligible speech, while "balderdash" might be more appropriate for describing nonsensical arguments.
It's also important to consider the tone you want to convey. Some terms, like "nonsense" and "drivel," are more neutral, while others, like "rubbish" and "crap," are more negative.