The antonyms for the word "most attritional" include "least strenuous," "easy," "gentle," "smooth," and "undemanding." These words convey the opposite meaning of "most attritional," which typically implies a prolonged and exhausting challenge or struggle. For instance, a task that is least strenuous requires minimal effort and poses no significant difficulty. Similarly, something that is easy can be completed without much effort or difficulty. A gentle activity or a smooth process causes no harm, stress, or discomfort. Finally, an undemanding task does not require much time, effort, or attention to complete.