IPA: //ˈkræs.nəs//
KK: /kræs.nəs/
The quality of being rude, insensitive, or lacking in refinement.
His crassness was evident in the way he spoke to his colleagues.
Crassness is formed from "crass" (from Latin "crassus", meaning thick or coarse) and "-ness" (a suffix indicating a state or quality). The word "crassness" refers to the quality of being thick, coarse, or lacking refinement.
Think of 'crass' meaning thick or coarse, and remember that 'crassness' describes the state of being thick or lacking refinement.