The term "clientages" refers to a group of clients, customers, or patrons of a particular business or organization. Antonyms for the word would be words that are opposite in meaning, such as "non-client" or "non-customer." Another antonym could be "competitor," as they would not be considered part of the clientage. Some other potential antonyms could be "opponent," "adversary," or "opposition," as they represent conflicting interests. It is important to understand antonyms as they can help to expand your vocabulary and provide a more precise understanding of language.