Principium, a Latin word, refers to the beginning or origin of something. Antonyms of principium would include: end, conclusion, termination, cessation, closure, finale, completion, finish, halt, and stoppage. These words represent the opposite of principium and convey a different meaning altogether. While principium implies the start or beginning of an event, process, or system, the antonyms suggest an end or a conclusion. The choice of the right antonym depends on the context of the sentence or the topic in which it is used. Overall, antonyms for principium help to express a complete thought or idea by representing the polarity at the end of the spectrum.