cheeseparing
culpably negligent
derelict
frugal
frugal to excess
inadvertent
inattentive
laissez-faire
lax
loose
neglectful
neglecting
negligent
noninterfering
nonrestrictive
off-guard
overfrugal
overly permissive
parsimonious
penny-wise
penny-wise and pound-foolish
permissive
procrastinating
relaxed
remiss
scrimping
skimping
slack
slighting
slurring
sparing
stinting
too frugal
uncircumspect
unguarded
unrigorous
unwary
unwatchful