general framework; outline; broad outline
Refers to the overall structure, rough plan, or big picture of something, without going into details.
まずは大枠を決めてから、細かい点を詰めましょう。
Let's decide on the general framework first, and then work out the details.
彼の説明は大枠では正しいが、細部に誤りがある。
His explanation is correct in broad outline, but there are errors in the details.
Compound of 大 (おお, 'big') and 枠 (わく, 'frame'). The literal meaning is 'big frame', which extended to 'general framework' or 'outline'.