expression, suru verb (irregular)
lose completely; waste; let slip away
Used when an opportunity, effort, or plan is completely lost or wasted, often through carelessness or misfortune.
せっかくのチャンスをふいにした。
I completely wasted a golden opportunity.
雨でピクニックの計画をふいにした。
The rain ruined our picnic plans.
無駄にする means to waste something in a general sense, while ふいにする emphasizes that something valuable is completely lost or ruined, often due to a specific event or mistake.
The exact origin is uncertain. ふい may be related to 不意 (unexpected), suggesting a sudden loss or failure.