Antonyms for the word "most stimulative" could include words like dull, boring, unexciting or uninteresting. These words describe things that have the opposite effect of stimulating, leaving one feeling bored or disinterested. Other antonyms could include words like lethargic, passive, sluggish or unenergetic. These words describe an absence of stimulation or energy, which is very different from the exciting, invigorating feeling that comes from something that is stimulative. When looking for antonyms for the word "most stimulative," it's important to keep in mind that you're looking for words that describe the opposite effect, rather than words that simply mean something different.