The word "most supereminent" suggests the highest degree of excellence or superiority in something. Antonyms for this phrase would be words that denote the opposite, such as: mediocre, average, inferior, ordinary, unremarkable, or run-of-the-mill. These antonyms describe things that are merely satisfactory or acceptable, lacking the exceptional qualities that set them apart. It's good to keep in mind that not everything needs to be the "most supereminent" to be worthwhile or valuable, as even the most ordinary things can hold significant meaning in our lives. Therefore, it's beneficial to appreciate things for what they are, without always seeking the highest level of excellence.