Undeviating means something that is constant and unchanging. Antonyms for undeviating can be words that express the opposite meaning, such as inconstant or variable. Inconstant describes something that is continually changing or not reliable, while variable refers to something that is subject to change or is unpredictable. Another antonym for undeviating is erratic, which means something that is inconsistent or having no fixed course. Finally, another antonym for undeviating could be deviating itself, which means varying or different from what is expected or normal. In conclusion, there are many possible antonyms to the word "more undeviating.