careless
deaf
indifferent
regardless
Lethean
absentminded
airy
aloof
amnestic
apathetic
arbitrary
ataractic
blase
blind
blocked
bored
capricious
casual
converted
cursory
degage
detached
devil-may-care
disinterested
dispassionate
disregardant
disregardful
distant
distracted
distrait
easygoing
feckless
flippant
forgetful
forgetting
free and easy
grasshopper
happy-go-lucky
impassive
improvident
inadvertent
inattentive
inclined to forget
inconsiderate
incurious
inexcitable
inobservant
insouciant
callous
heartless
ignorant
imprudent
impulsive
irresponsible
oblivious
profligate
reckless
senseless
thoughtless
uncaring
unmindful
unrestrained
wanton
wayward