Which is the best term to describe when a researcher lives in particular culture for an extended time order gain detailed understanding and description of culture?

The best term to describe a researcher living in a particular culture for an extended time to gain a detailed understanding and description of the culture is participant observation.

Here's why:

* Participant observation is a research method used in anthropology and other social sciences where the researcher immerses themselves in the culture they are studying, participating in daily life and observing the people and their interactions.

* This method allows for a deep understanding of the culture's norms, values, beliefs, and practices.

* It contrasts with other methods, such as ethnography, which focuses on the written description of a culture, or fieldwork, which is a broader term encompassing various research methods in a specific setting.

While other terms like "immersion" or "ethnographic fieldwork" are relevant, participant observation captures the core element of the researcher actively participating in the culture while observing it.