Real Dictionary

culture shock
Culture shock is a feeling of anxiety, loneliness, and confusion that people sometimes experience when they first arrive in another country.

culture shock in American English
the alienation, confusion, surprise, etc. that may be experienced by someone encountering unfamiliar surroundings, a strange city or community, a different culture, etc.
noun: a state of bewilderment and distress experienced by an individual who is suddenly exposed to a new, strange, or foreign social and cultural environment

culture shock in British English
noun: the feelings of isolation, rejection, etc, experienced when one culture is brought into sudden contact with another, as when a primitive tribe is confronted by modern civilization