The phrase "more slivered" refers to something that has been cut into thin, narrow pieces. The antonyms for this term would be "thickened," "widened," or "enlarged." These words imply that something has become broader, larger, or thicker than before. For example, a piece of wood could be "thickened" by adding layers of veneer to it. Conversely, if something is "slivered," it could be said to be "narrowed" or "whittled down." These words suggest that something has been reduced in size or made more slender, leaner, or refined. The antonyms for "more slivered" highlight the dual nature of cutting and remodeling processes.