The antonyms for the word "most unexcitable" can be numerous depending on the context. Some of the possible antonyms could be "excited," "lively," "energetic," "enthusiastic," "animated," "passionate," "zealous," or "thrilled." These opposite words suggest that someone who is not unexcitable would be experiencing a high level of emotion or excitement in a given situation. Therefore, they might be easily aroused, vibrant, and zealous about things that they are interested in. On the other hand, some antonyms could be "calm," "tranquil," "composed," "serene," or "placid," meaning that the person wouldn't easily become stirred up or agitated even in tense or stressful situations.