1 unite, unify, join, connect, relate, link, conjoin, band, ally, associate, integrate, merge, pool:
Combine forces, and we'll win.
2 blend, mix, amalgamate, mingle, consolidate, compound, incorporate, put together:
Combine the water, butter, and salt in a saucepan.
3 blend, fuse, synthesize, bind, bond, compound, unite, coalesce, come together, commingle, mingle:
When heated, the silver combines with the chlorine.