(a.) Causing loss of memory.

Lethean absent absorbed abstracted amnestic bemused blocked castle-building converted daydreaming daydreamy distracted distrait dreaming dreamy drowsing ecstatic elsewhere engrossed faraway forgetful forgetting half-awake heedless in a reverie in a trance in the clouds inadvertent inattentive inclined to forget lost lost in thought meditative mooning moonraking museful musing napping nodding oblivious off pensive pipe-dreaming preoccupied rapt repressed somewhere else stargazing suppressed taken up transported unaware unconscious unheedful unheeding unmindful unnoticing unobserving unperceiving unseeing withdrawn woolgathering wrapped in thought