/ ˈrɪgərəs; NAmE / adjective
1.
done carefully and with a lot of attention to detail
SYN thorough :
a rigorous analysis
2.
demanding that particular rules, processes, etc. are strictly followed
SYN strict :
The work failed to meet their rigorous standards.
► rig·or·ous·ly adverb :
The country's press is rigorously controlled.
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WORD ORIGIN
late Middle English : from Old French rigorous or late Latin rigorosus , from rigor stiffness, from rigere be stiff.