The antonym for the word "most stewardly" refers to actions that are not responsible or careful. Some possible antonyms for stewardly could include wasteful, careless, negligent, reckless, imprudent, or extravagant. These words suggest a lack of concern for the proper management of resources or a disregard for the consequences of one's actions. For instance, a wasteful person might use too much water, electricity or other resources without regard for conservation or economy, while a careless person might make mistakes and cause damage through their lack of attention or preparation. Conversely, a stewardly person is diligent, reliable, cautious, and proactive in protecting and preserving resources.