rigorous

A rigorous person or process is one that's very thorough and careful.

When people say something is rigorous, they often mean it's demanding and exacting. For example, a math problem might require rigorous calculation to get the answer right. If someone does research rigorously, they'll carefully examine all the data and evidence before coming to conclusions. In education, a course might be designed to be rigorous, meaning students have to work hard to understand complex ideas and concepts. Even in sports, a coach might want their team to play with a rigorous focus, giving 100% effort on the field or court.