absent

AWOL, truant

departed, gone, retired

abroad, vacationing

dead, departed, extinct, lost, perished, vanished

defunct, done, expired, finished, lapsed, obsolete, over, passé

inadequate, insufficient, rare, scarce, sparse, uncommon

absorbed, daydreaming, dreaming, dreamy, engrossed, faraway, intent, pensive, rapt

heedless, inattentive, insensible, oblivious, unaware, unconscious, unheeding, unknowing, unmindful, unperceptive, unthinking, unwary, unwitting, vacant

befogged, befuddled, bemused, bewildered, birdbrained, clueless, confused, dazed, flighty, foggy, forgetful, forgetting, hazy, muddled, scatterbrained, unfocused (also unfocussed)