2 synonym groups for Unbeeindruckend

mediocre, average, fair, middling, passable, moderate, tolerable, unremarkable, indifferent, ordinary, run-of-the-mill, okay, acceptable, not bad, decent, satisfactory, all right, not great, not terrible, nothing special, commonplace, standard, usual, workaday, garden-variety, humdrum, lackluster, pedestrian, prosaic, vanilla, unexceptional, undistinguished, uninspired, unmemorable, unnoteworthy, plain, nondescript, second-rate, second-class, subpar, so-so, fair-to-middling, middle-of-the-road, fairish, passably [x]

weakly, feebly, ineffectively, sluggishly, listlessly, half-heartedly, unenthusiastically, indifferently, apathetically, spiritlessly, languidly, limply, dully, lifelessly, inertly, torpidly, lackadaisically, lethargically, unenergetically, faintly, flaccidly, unspiritedly, unvigorously, unanimatedly, unforcefully, unpowerfully, unresolutely, unsteadily, unstrongly, unvitalized, weak-kneed, wimpily, wimpishly, spinelessly, pusillanimously, tremulously, falteringly, irresolutely, vacillatingly, waveringly, indecisively, unassertively, unconfidently, diffidently, timorously, fearfully, nervously, apprehensively, hesitantly [x]