IPA: /ˈstaɪl.ləs.nəs/
KK: /ˈstaɪlˌlɛs.nəs/
A lack of distinctive or unique style in appearance, behavior, or expression.
The room's stylelessness made it feel cold and uninviting.
Stylelessness → It is formed from "style" (from Old French *estile*, meaning a manner of doing something) and "-lessness" (meaning without). The word "stylelessness" means the state of being without style or a distinctive manner.
Think of 'style' as a way of doing things, and '-lessness' means without — so stylelessness refers to lacking a distinctive way.