Pachydermous is an uncommon word that is used to describe animals with thick skin, like elephants, rhinoceroses, and hippos. However, there are several synonyms for this word, including thickskinned, tough, callous, and insensitive. These words can be used to describe a person who is emotionally strong, or someone who is impervious to criticism. Thickskinned is also commonly used to describe a person who is not easily offended or affected by insults or criticisms. Meanwhile, callous and insensitive are used to describe someone who lacks sensitivity and empathy towards others. Overall, these synonyms for pachydermous are useful for describing both animals and people with thick skin.