IPA: /ˈvɛstləs/
KK: /ˈvɛstləs/
Not wearing a vest or lacking a vest.
He felt a bit cold because he was vestless at the party.
Vestless → It is formed from "vest" (from Latin "vestis", meaning garment or clothing) and "-less" (meaning without). The word "vestless" means without a vest or garment.
Think of 'vest' as a type of clothing and '-less' meaning without — so vestless means without a vest.