Antonyms of adj purposeful

2 senses of purposeful

Sense 1
purposeful (vs. purposeless) -- (serving as or indicating the existence of a purpose or goal)

purposeless (vs. purposeful) -- (not evidencing any purpose or goal)
        => adrift (predicate), afloat (predicate), aimless, directionless, planless, rudderless, undirected -- (aimlessly drifting)
        => desultory -- (marked by lack of definite plan or regularity or purpose; jumping from one thing to another; "desultory thoughts"; "the desultory conversation characteristic of cocktail parties")

Sense 2
purposeful -- (having meaning through having an aim; "led a happy purposeful life")

INDIRECT (VIA meaningful) -> meaningless, nonmeaningful -- (having no meaning or direction or purpose; "a meaningless endeavor"; "a meaningless life"; "a verbose but meaningless explanation")

Similarity of adj purposeful

2 senses of purposeful

Sense 1
purposeful (vs. purposeless) -- (serving as or indicating the existence of a purpose or goal)
       => businesslike, earnest -- (not distracted by anything unrelated to the goal)
       => goal-directed, purposive -- (having a purpose; "purposive behavior")
       => purpose-built, purpose-made -- (designed and constructed to serve a particular purpose)
          Also See-> meaningful#1; resolute#1

Sense 2
purposeful -- (having meaning through having an aim; "led a happy purposeful life")
       => meaningful (vs. meaningless) -- (having a meaning or purpose; "a meaningful explanation"; "a meaningful discussion"; "a meaningful pause")