WelcomeOriginally Posted by Fredrik
I believe you are both correct. -less is the opposite of -ful, which makes careful and careless opposites. uncarefulis not a recognized word.
There is a difference in meaning between not careful and careless,
EX: If you are not careful, you're going to fall. (i.e., If you're not cautious)
EX: I was careless. (i.e., I wasn't thinking; I was insensitive; I was not concerned about X.)
EX: I wasn't careless. (i.e., I was thinking; I was concerned about X.)
EX: I wasn't careful. (i.e., I wasn't cautious; I should have been more cautious.)
All the best, :D