Cross-cultural describes anything that involves two or more cultures at the same time, or that reaches from one culture into another: a cross-cultural marriage, cross-cultural training, a cross-cultural study of how people say sorry. It goes in front of a noun. The word is common in education, business and research writing — companies run cross-cultural training before sending staff abroad, and researchers do cross-cultural studies to see whether something true in one country is true anywhere else. Notice what it does not mean. It does not mean foreign, and it does not mean multicultural. Multicultural describes one place holding many cultures inside it — a multicultural city. Cross-cultural describes the movement or comparison between them — what happens where two cultures touch. So a class with students from ten countries is multicultural; the misunderstanding that happens in that class when a Japanese student's silence is read as disagreement is cross-cultural. There is also intercultural, used almost the same way, slightly more common in Europe and in teaching; if you learn cross-cultural you can read both. The word usually carries a friendly, curious feeling — it is the vocabulary of people trying to understand each other, not of conflict.