IPA: /ˈslɒpɪnəs/
KK: /ˈslɑːpɪnəs/
The quality or state of being careless or messy in work or appearance.
His sloppiness in completing the project led to many mistakes.
Sloppiness is formed from "sloppy" (originating from the dialectal English word 'slop', meaning to spill or overflow) and the suffix "-ness" (meaning the state or quality of). The word describes the state of being messy or careless.
Think of 'sloppy' as being messy or overflowing, and '-ness' indicates a state. So, sloppiness means the state of being messy.