nopperi
Lacking definition, features, or character. Describes a flat face, a bland landscape, or a monotonous surface.
💡Driving through flat farmland — 'The landscape was nopperi with nothing in sight.'
のっぺりとした顔で表情が読めない。
His nopperi flat face made it impossible to read his expression.
The building's ___ concrete walls gave it a cold, institutional feel.
○○としたコンクリートの壁が冷たい印象を与えた。