The phrase "most slivered" denotes the maximum amount or degree of something that has been cut into thin, narrow pieces. Some antonyms for this phrase could include "whole," "intact," "unbroken," or "solid." These terms suggest a sense of completeness or wholeness, which is the opposite of being slivered. Other antonyms could include "thick," "chunky," "coarse," or "large," which indicate a larger size or shape that is not easily sliced into slivers. In general, the antonyms for "most slivered" describe things that are not fragmented or divided into small, narrow pieces, but rather are more complete, substantial, or voluminous.