IPA: /ˈkliːn.nəs/
KK: /ˈklēn.nəs/
The quality or state of being clean, free from dirt or impurities.
The cleanness of the kitchen impressed the health inspector.
Cleanness is formed from "clean" (from Old English *clæne*, meaning free from dirt or uncleanliness) and "-ness" (meaning the state or quality of). The word "cleanness" refers to the state of being clean or free from dirt.
Think of being 'free from dirt' ('clean') and the '-ness' indicating a state. This helps you remember that 'cleanness' means the quality of being clean.