na-adjective, noun which may take the genitive case particle 'no', noun
chubby; slightly overweight; plump
Describes a body type that is somewhat overweight but not extremely so; often used for people or body parts. Can be used as a noun or adjectivally.
彼は中太りの体型だ。
He has a chubby build.
中太りの指に合う指輪を探している。
I'm looking for a ring that fits my plump fingers.
Compound of 中 (ちゅう, 'medium') and 太り (ふとり, 'fatness'), literally 'medium fatness'. The exact historical derivation is uncertain, but the word straightforwardly describes a moderate degree of overweight.