The word "most zero" does not have a recognized antonym. The phrase itself is an oxymoron, as "most" implies a large amount, while "zero" means nothing. However, if we break down the word "most" into its meaning of "the largest part," we can consider "least non-zero" as an antonym. This phrase implies the smallest amount that is not zero. Another potential antonym could be "most abundant," which suggests the highest quantity of something. Still, it's important to note that "most zero" is not commonly used and that even its possible antonyms may not be entirely accurate.