The word "up-ends" refers to the act of overturning or flipping something over. Some antonyms for this word would be terms that relate to keeping objects right-side up or stable, such as "settle," "balance," "stabilize," or "secure." These antonyms describe actions or conditions that prevent things from tipping over or becoming unstable. "Settle" suggests the act of making something firm or steady, while "balancing" refers to keeping something evenly weighted or distributed. "Stabilize" implies making something resistant to movement or shaking, and "secure" connotes making something firmly fastened or held in place. All of these antonyms contrast with the notion of up-ending, or turning something over.