I was doing an exercise that requires that blank spaces be filled in by writing an appropriate form of a given word. So, here my sentence goes:

"The _____ of the remark ha made just takes my breath away." (THINK)

My answer was "unthoughtfulness" (which I later found in this dictionary ), but the given answer is "thoughtlessness".
How do you feel about these two words? Is there any difference in meaning between the two or is it a matter of which one is more natural or common?

Many thanks! Emotion: smile
I'm trying to think if there's some philosophical difference, but I can't find one. The antonym is the same for both thoughtless and unthoughtful, so I think they are basically identical.

Thoughtlessness is more natural, and shows a better economy of syllables, 3 syllables as opposed to 4.
Thanks, Gordon! Emotion: smile

Philosophical differences would be too suble to be tested in this type of test (the CPE), so I'll buy your explanation about thoughtlessness being more natural.