Osmic acid, also known as osmium tetroxide, is a highly toxic and volatile compound used in various laboratory applications. However, there isn't a direct antonym for the word "osmic acid" as it is a specific chemical compound.
Antonyms, in general, are words that have opposite meanings to a particular word. For instance, antonyms for "soft" could be "hard", "firm", or "solid". However, for "osmic acid", we could look at alternative compounds that are non-toxic and non-volatile. For example, "sodium chloride", also known as table salt, is an inert and harmless chemical compound used in culinary applications.