The curvature built into a club's sole — front to back (leading edge to trailing edge), heel to toe, or both. Camber shrinks the patch of sole actually touching the ground at impact, so the club rocks through the turf rather than plowing it, making the stamped bounce more forgiving across different attack angles and lies. A flat, uncambered sole presents its full width to the ground and is fussier about a perfect strike. "Four-way camber" means curvature in both directions at once. Fairway woods and hybrids carry pronounced camber for the same reason — it's much of why a hybrid is so much friendlier than a long iron from imperfect lies.