Rat packs usually refer to groups of rats. However, if one were to look for antonyms for this term, a few options could include "solitude," "lone rat," or "single rat." These antonyms suggest the opposite of the term rat pack, which implies a gathering or a group of rats. Another antonym could be "cleanliness," which implies the opposite of the negative connotations associated with rats. In any case, antonyms for rat packs may not often be used, as the term usually refers to uninvited and unwanted guests, regardless of whether they come alone or in a group.