The word "flatout" is often used to describe something done at maximum effort or speed. However, there are several antonyms for flatout that indicate a different approach or pace. An antonym for "flatout" could be "slowly," "casually," or "moderately." These words suggest a more sluggish or relaxed approach to tasks, rather than the fast, intense pace associated with "flatout." Another antonym for "flatout" could be "halfheartedly," indicating a lack of enthusiasm or effort rather than full-on commitment. Other antonyms could include "indifferently," "carelessly," or "halfheartedly," all of which suggest a lack of passion or dedication.