noun
visiting researcher
A researcher affiliated with an institution on a temporary or non-permanent basis, often from another university or organization.
彼は客員研究員としてこの大学に来ています。
He is here at this university as a visiting researcher.
客員教授 is a visiting professor, a higher academic rank than 客員研究員.
Compound of 客員 (visiting member) and 研究員 (researcher).