The word "advoutress" may not be common in modern language, but it does have several synonyms that can be used in its place. These synonyms include "mistress," "courtesan," "paramour," "concubine," and "kept woman." All these words refer to a woman who is involved in an illicit relationship with a married man. Each of these words also has its own nuances and connotations. For example, "courtesan" suggests a more sophisticated and refined woman compared to "mistress," which has a more negative or disapproving connotation. Regardless of which word is used, it is important to remember that such relationships are frowned upon in many cultures and societies.