amnesiac
amnesic
inattentive
Lethean
absent
absent-minded
absentminded
abstracted
airy
amnestic
bemused
blocked
careless
casual
converted
cursory
degage
disregardant
disregardful
distracted
dreaming
dreamy
easygoing
flippant
forgetting
free and easy
heedless
in the clouds
inclined to forget
inconsiderate
indifferent
insouciant
lax
lazy
lethean
mindless
neglectful
negligent
oblivious
offhand
out of it
perfunctory
preoccupied
reckless
regardless
remiss
averse
bereave
credulous
deaf
delude
deprave
disobedient
insensible
thoughtless
unable
unconcerned
ungrateful
unkind
unmindful
unreliable
unwilling
valueless
fretful
regretful