Antonyms for the phrase "rhyme reason" include illogical, irrational, senseless, nonsensical, baseless, unreasoning, and unreasonable. These words represent a lack of order, coherence, and justification, which is opposite to what is conveyed by "rhyme reason." While "rhyme reason" implies that there is meaning and purpose behind something, these antonyms indicate the absence of such factors. They suggest that something is done without any rationale or logic or that it is beyond comprehension or understanding. In this sense, these antonyms highlight the importance of reason and logic in making sense of the world around us.