The antonyms for the word "most longish" can vary depending on the context in which the term is used. However, common antonyms for it could be "short," "brief," "concise," "succinct," "terse," and "abridged." These antonyms represent the opposite of something that is "longish," implying that they refer to something that is relatively short or brief. Colorful descriptions could also be used, such as "snug," "cramped," "curtailed," or "truncated." In any case, these antonyms connote a sense of limitation or constraint, evoking the idea of cutting down or reducing something.