IPA: /ˈpæt.ərn.ləs/
KK: /ˈpætərnləs/
Something that does not have a specific design or arrangement; it appears random or without any recognizable structure.
The fabric was patternless, making it suitable for various styles.
Patternless → It is formed from "pattern" (from Old French *patron*, meaning a model or design) and "-less" (meaning without). The word "patternless" means without a pattern or design.
Think of a 'model' or 'design' ('pattern') that is 'without' ('-less') — that's what patternless means.