Antonyms for the word "most astonished" would include words such as unsurprised, unperturbed, unaffected, unshocked, impassive, and stoic. These antonyms carry the opposite meaning of being astonished, amazed, or shocked. When someone is unsurprised, they are not caught off guard or taken aback by unexpected events. If someone is unperturbed, they remain calm and cool-headed in the face of adversity. An unaffected person remains unimpressed by what they see or hear, whereas an unshocked person has seen it all before. Being impassive means lacking emotion or being unresponsive, and a stoic person is able to endure pain, hardship, or disappointment without complaint or showing emotion.