There is no widely accepted definition or practice called "cosmic breathing." This term is not commonly used in any scientific, medical, or spiritual context.

It's possible that "cosmic breathing" is:

* A neologism: A newly coined word, perhaps referring to a specific breathing technique developed by an individual or group.

* A metaphorical term: Used to describe the feeling of being connected to something larger than oneself, perhaps associated with meditation or spiritual experiences.

* A misunderstanding: Perhaps a misinterpretation of a similar term, like "pranayama" (a yogic breathing practice) or "cosmic consciousness" (a philosophical concept).

If you encountered this term in a specific context, please provide more information so I can help you understand its meaning.