pumpkin

Alteration of pompion, pumpion (“pumpkin”) with the diminutive -kin, from Middle French pompon, from Latin pepō (whence English pepo), from Ancient Greek πέπων (pépōn, “large melon”), from πέπων (pépōn, “ripe”), from πέπτω (péptō, “ripen”). The first attestation is from 1647.

The alternative theory that it may be from Massachusett pôhpukun (“grows forth round”) is false.

The automotive sense is by fancied resemblance.