ぺたんこ

Adjectival nouns or quasi-adjectives (keiyodoshi), nouns which may take the genitive case particle 'no', onomatopoeic or mimetic word

Noun (common) (futsuumeishi), colloquialism, manga slang

Noun (common) (futsuumeishi), onomatopoeic or mimetic word

三辺さんぺん

three sides (length, width and height)

こんこん

this

隣辺りんぺん

adjacent side; cathetus

本編ほんぺん

original story (as opposed to a sequel, spin-off, etc.); main story; main part(s) of a story

弾片だんぺん

shrapnel; shell or bullet fragment