The term "out gas" refers to the release of gases from materials or substances, such as during chemical reactions or heating processes. Some antonyms of this word include "absorb," "retain," and "contain." Rather than releasing gases, these antonyms would suggest that the material or substance is instead absorbing or holding onto gases. Other antonyms could include "restrict," "reduce," or "limit," which would suggest that the release of gases is being controlled or minimized. It's important to consider these various antonyms in different contexts, such as in environmental or industrial situations where the release of gases may have different implications.