一概に
いちがいに unconditionally; as a rule
Why it means this
一 (one) + 概 (a general measure — a level-stick struck across a grain measure) + に — 'sweeping everything level'; used with a negative, 'not necessarily, not as a blanket rule' (一概には言えない).
Breakdown
Each character links to its full entry — origin story, stroke order, and readings.