Most playacting usually refers to when someone is pretending or acting out a situation, often in a dramatic or exaggerated manner. Antonyms for the phrase most playacting could include sincerity, authenticity, genuineness, honesty, and truthfulness. In these cases, the opposite of playacting would be when someone is being genuine or truthful in their actions and words, rather than faking or exaggerating things for effect. Antonyms could also include seriousness, solemnity, or sobriety, which all suggest a more sincere or serious approach that is the opposite of playacting's often theatrical or exaggerated style.