noun which may take the genitive case particle 'no', na-adjective, noun
Colloquial adjective-like use (often derogatory) describing someone or something as fat or chubby. Can be used with な or の.
最近ちょっとデブになったかも。
I might have gotten a bit fat lately.
あのデブな猫、かわいいね。
That chubby cat is cute, isn't it?
noun
Colloquial noun referring to a fat person; often derogatory and insulting. Use with caution.
あいつはただのデブだ。
That guy is just a fatso.
The exact derivation is uncertain; likely a sound-symbolic or mimetic word related to the idea of being plump or swollen.