The antonyms for the word "most unpeaceful" are "peaceful," "calm," "serene," "quiet," "tranquil," and "harmonious." Peaceful refers to a state of calmness without disturbance or conflict. Calm refers to a state of tranquility without agitation or mental turmoil. Serene means being tranquil, calm, and placid. Quiet refers to a state of silence, stillness, or the absence of disturbance. Tranquil means being in a peaceful or calm state where there is no disturbance. Finally, Harmonious implies a state of agreement or harmony where everything is in balance and there is no discord. These antonyms denote a sense of calmness and tranquility, devoid of anxiety, disorder or conflict.