IPA: /ˈplʌmpɪst/
KK: /plʌmpɪst/
The largest or most rounded in shape, often used to describe someone or something that is pleasantly full or chubby.
The plumpest fruit on the tree was the sweetest.
Comparative: plumper
Superlative: plumpest
Plumpest → It is formed from "plump" (of uncertain origin, possibly from Middle English *plumpe*, meaning to fall heavily or to be rounded) and the superlative suffix "-est" (meaning most). The word "plumpest" refers to the state of being the most rounded or full in shape.
Think of something that has fallen heavily and become rounded — that's what 'plump' means, and adding '-est' indicates it is the most rounded.