1. slang Someone who is not sincere, genuine, or trustworthy. The phrase is a humorous, mock Latin variant of "phony baloney." That guy's a total phonus balonus—you can't trust a word he says.
2. slang Nonsense or foolishness. Oh please, that homeopathy stuff is total phonus balonus.
Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.