Penetralias is a somewhat rare word that refers to the innermost or most secret parts of something, like the private thoughts of a person or the hidden corners of a building. While there is no exact synonym for this term, there are several antonyms that might come to mind. For example, the opposite of penetralias could be the exterior or surface of something, the public or overt aspects of a person or institution, or the easily accessible parts of a structure or system. Other potential antonyms might include words like superficial, obvious, exposed, or blatant. Ultimately, the antonym of penetralias will depend on the context and usage of the word.