2 synonym groups for Stumpf

boring, tedious, uninteresting, monotonous, dreary, drab, lackluster, lifeless, uninspiring, humdrum, mind-numbing, wearisome, tiresome, flat, bland, insipid, vapid, prosaic, mundane, colorless, unstimulating, uneventful, repetitive, unimaginative, unexciting, soporific, stodgy, banal, trite, pedestrian, jejune, plodding, unvaried, unremarkable, unentertaining, spiritless, listless, deadening, numbing, enervating, unappealing, uninviting, unadventurous, unthrilling, unamusing, unengaging, lackadaisical [x]

apathy, lethargy, indifference, listlessness, ennui, languor, torpor, dullness, inertia, passivity, sluggishness, weariness, fatigue, disinterest, unenthusiasm, lack of energy, lack of spirit, lack of vitality, lack of zest, lack of drive, lack of motivation, lack of enthusiasm, lack of interest, lack of liveliness, lack of vigor, lack of animation, lack of excitement, lack of fervor, lack of passion, lack of ardor, lack of zeal, lack of dynamism, lack of verve, lack of pep, lack of spunk, lack of gumption, lack of get-up-and-go, lack of oomph, lack of spark, lack of fire, lack of gusto, lack of moxie, lack of pluck, lack of vim, lack of zing, lack of zip, lack of zestfulness, lack of effervescence [x]