Synonyms For "Careless" :

2 syllables:

artless, heedless, offhand, offhanded, passing, reckless, slapdash, slipshod, sloppy

3 syllables:

casual, cursory, haphazard, imprudent, incautious, negligent, regardless, unconcerned

4 syllables:

inattentive, perfunctory, superficial