严谨 (yán jǐn): строгий

The data analysis in this paper is very rigorous; every experimental step is recorded in detail, so the conclusions are highly credible.

He has always been rigorous in his work; he even checks meeting materials three times before he feels at ease.

Learning a foreign language requires a rigorous attitude; you can't just guess word meanings by feeling—you need to consult a dictionary and understand usage.

This engineer's design plan is very rigorous, taking various extreme weather conditions into account, and thus won unanimous approval from the team.

The mother is very rigorous about her child's diet management, ensuring balanced nutrition every day and never allowing too many snacks.