noun
skinny person; scrawny person; scarecrow; bag of bones
Colloquial and mildly derogatory term for a very thin person, often used teasingly or self-deprecatingly.
あの子は痩せっぽちで、いつも風に飛ばされそうだ。
That kid is so skinny, he always looks like he might get blown away by the wind.
子供の頃は痩せっぽちだったけど、今は普通体型だよ。
I was a bag of bones as a child, but now I have a normal build.
痩せ型 is a neutral descriptor for a slim body type, while 痩せっぽち is more colloquial and often carries a negative or teasing nuance.
ガリガリ is an onomatopoeic term meaning 'skin and bones' and is more emphatic and informal than 痩せっぽち.
Derived from the verb 痩せる (yaseru, 'to become thin') with the suffix っぽち (-ppochi), which adds a diminutive or derogatory nuance. The exact origin of っぽち is uncertain, but it may be related to ぽっちり (potchiri, 'small amount') or similar sound-symbolic forms.