intercultural是一个合成词 也就是inter cultrual 就是不同文化之间的意思 而intercultrual communication自然就是文化与文化之间的交流的意思。

or if you really prefer an English version of the explaination, intercultural simply means between two or more different cultures. like the word intercity means between two different cities. so intercultrual communication means the communication between two or more different cultures.