Synonyms and related words :
aimless, baffling, bewildering, casual, causeless, confounding, designless, driftless, dysteleological, enigmatic, enwrapped in mystery, haphazard, incomprehensible, indecipherable, indefinable, indescribable, indiscriminate, inextricable, inscrutable, insoluble, insolvable, mindless, mysterious, mystic, mystifying, odd, peculiar, perplexing, promiscuous, purposeless, puzzling, random, stochastic, strange, stray, unaccountable, undefinable, undirected, unexplainable, unfathomable, unintelligible, uninterpretable, unmotivated, unsolvable