IPA: /ˈsɛksiəst/
KK: /ˈsɛksɪəst/
The most attractive or appealing in a sexual way.
She wore the sexiest dress at the party, turning everyone's heads.
Comparative: sexier
Superlative: sexiest
Sexiest → It is formed from "sex" (from Latin "sexus", meaning gender or sex) and the superlative suffix "-iest" (meaning most). The word "sexiest" refers to the most sexually attractive or appealing.
Think of the word 'sex' which relates to gender or attraction, and remember that 'sexiest' means the most attractive in that context.