To intermarry means to marry someone from a different group than your own. The groups might be defined by religion, culture, ethnicity, or social class. When a Catholic marries a Protestant, or when families from different cultural backgrounds join through marriage, they intermarry.

Throughout history, some communities encouraged intermarriage to build alliances and strengthen bonds between different groups. Other communities discouraged or even forbade it, wanting to preserve their traditions and identity. Today, intermarriage between people of different religions, cultures, and backgrounds is common in many parts of the world.

The word can also describe what happens when members of two groups marry each other regularly over time. When historians say that two communities intermarried, they mean that marriages between the groups became common, often leading to closer ties and shared traditions. For example, when neighboring kingdoms intermarried, their royal families became connected, sometimes preventing wars or forming political alliances.

Intermarry specifically describes marriages that cross group boundaries. When two people from the same background marry, that's simply marriage. When their union bridges different communities or traditions, that's intermarriage. The crossing of those boundaries is what makes it intermarriage.