Phocidae, also known as the true seals, is a family of aquatic mammals that includes 19 species. While there may not be an extensive list of synonyms for the word Phocidae, there are a few alternative names that could be used. One alternative name is "earless seals," which distinguishes this family from the eared seal family, Otariidae. Another option is "hair seals," as many species in this family have thick coats of fur to keep them warm in cold waters. Finally, "true seals" is also a commonly used alternative name for Phocidae, as it emphasizes the fact that these seals lack external ear flaps and have a distinct body shape compared to other seal species.