While the term "pantheress" may not be commonly used in everyday language, there are several synonyms available to describe a female panther, or a woman who possesses panther-like characteristics. Some possible options include "panthera," "pantherine," "black cat," and "cat woman." These words all convey a sense of power, strength, and stealthiness - qualities often attributed to the panther - and can be used to describe a wide range of things, from a sleek and mysterious feline to a confident and assertive woman. Ultimately, the choice of synonym will depend on the context in which it is used and the specific connotations that the writer or speaker wishes to convey.