To join together or form a partnership/association; also to grapple or engage physically with someone (context-dependent).
二つの会社が組み合って新商品を開発した。
Two companies joined forces to develop a new product.
レスラー同士が組み合って技の取り合いになった。
The wrestlers grappled with each other, exchanging holds.
素材の性質がうまく組み合って、より強い材料ができた。
The properties of the materials combined well, producing a stronger material.