The antonyms for the term "lets air out" can include various phrases like keeping things private, concealing secrets, and hiding one's emotions. Some other antonyms for this term can be keeping things sealed, containing, closing off, or locking away. These opposing terms all suggest a lack of openness, honesty, and transparency. When something is being "aired out," it is being brought into the open for discussion, inspection, and evaluation. Conversely, when something is being kept private or sealed off, it remains hidden from view and cannot be scrutinized or debated. Thus, the antonyms for "lets air out" suggest a lack of communication, trust, and accountability.