The phrase "most featherlike" implies something that is light and airy, perhaps with delicate or wispy qualities. Its antonyms, then, would be words that describe something heavy, dense, or robust. Some antonyms for "most featherlike" could include "bulky," "dense," "solid," or "weighty." Alternately, one might consider "rough," "coarse," or "clumsy" to be antonyms of "most featherlike," as these words describe textures or movements that are jarring, rather than graceful. Overall, the antonyms for "most featherlike" suggest qualities that are the opposite of lightness and delicacy, conveying a sense of weight, solidity, or roughness.