Other forms: ethnographically
Anything that describes a specific culture's customs, like a movie about a small village in China or a book about French Canadians, can be described as ethnographic.
You're most likely to hear the word ethnographic in an anthropology class, since it's a scientific way to describe books, films, research, or lectures that have to do with the study of human societies and their customs. The word comes from two Greek roots, ethnos, or "people," and grapho, "to write." So if you write a paper about the customs of American teenagers in the 1980s, your work is ethnographic.