The antonyms for the word "more leakproof" can be "leaky," "permeable," and "porous." These antonyms refer to the ability of a substance or material to allow fluids or gases to pass through easily, without any barrier, and without retaining them. Leaky refers to something that has leaks, gaps, or holes that allow liquids or gases to escape, while permeable means that something is easily penetrated, allowing the passage of substances through it. Porous, on the other hand, refers to a substance that has small holes or spaces that allow liquids or gases to pass through. These antonyms are relevant in various fields such as plumbing, construction, and manufacturing, where leakproof materials are desirable.