What is another word for secret lingo?

Here are some alternatives to "secret lingo", depending on the specific context:

General:

* Code

* Cipher

* Jargon

* Slang

* Cant

* Argot

* Private language

* Secret language

* Underground language

More specific:

* Pig Latin: A playful code for children.

* Gibberish: A nonsensical language.

* Sign language: A visual language used by the deaf.

* Street slang: Language used in a specific community.

* Hacker slang: Language used by computer hackers.

* Military code: A highly secret language used by the military.

The best word to use will depend on the specific meaning you want to convey.