IPA: /ˈprɪtiər/
KK: /ˈprɪtiər/
More attractive or pleasing in appearance than something else.
She wore a prettier dress than her sister.
Prettier → It is formed from "pretty" (from Middle English *prity*, meaning clever or cunning) and "-er" (meaning one who). The word "prettier" means one who is more pretty or attractive than another.
Think of someone being 'more attractive' — 'pretty' describes attractiveness, and '-er' indicates a comparison.