The word "splenetic" refers to a person who is ill-tempered, irritable, and easily angered. Therefore, antonyms for "most splenetic" would be calm, serene, peaceful, tranquil, patient, and composed. A calm and serene person is someone who remains composed even in the worst of situations. They are peaceful and do not get irritated easily. A tranquil person is someone who is peaceful, free from worry or disturbance, and remains relaxed. A patient person is someone who remains calm even when faced with challenges and provocation. Being patient helps a person stay composed and serene. Therefore, the antonyms for "most splenetic" are positive qualities that can help one lead a peaceful and fulfilling life.