"Most serried" is a phrase suggesting something tightly arranged, compact, and closely packed. The antonyms for this phrase would be loose, scattered, disordered, and unordered. If we consider a group of people standing in a line, "most serried" would mean that they are standing shoulder to shoulder, without any gaps or spaces between them. A loose or disordered line, on the other hand, would have people standing with some distance between them or standing at slightly different angles or heights. The antonyms suggest a lack of uniformity in spacing or arrangement and a more relaxed or disorganized state.