• rigourous (misspelling; rare, archaic)

Inherited from Middle English rigorous, from Middle French and Anglo-Norman rigoreus, derived from Late Latin rigōrōsus (stiff, rigid; inflexible). By surface analysis, rigor +‎ -ous.

• IPA^(key): /ˈɹɪɡəɹəs/

• Audio (US):

  (file)

• Rhymes: -ɪɡəɹəs

rigorous (comparative more rigorous, superlative most rigorous)

1. Showing, causing, or favoring rigour/rigor; scrupulously accurate or strict; thorough.

   a rigorous officer of justice

   a rigorous execution of law

   a rigorous inspection

   • 1946 November and December, “George Westinghouse, 1846-1914”, in Railway Magazine, page 375:

     From this time onwards, the Westinghouse air brake literally went from strength to strength, and was triumphantly justified in the course of rigorous trials, both on the Pennsylvania Railroad and at Newark-on-Trent in this country.

   • 2013 August 3, “Boundary problems”, in The Economist, volume 408, number 8847:

     Economics is a messy discipline: too fluid to be a science, too rigorous to be an art. Perhaps it is fitting that economists’ most-used metric, gross domestic product (GDP), is a tangle too. GDP measures the total value of output in an economic territory. Its apparent simplicity explains why it is scrutinised down to tenths of a percentage point every month.

2. Severe; intense.

   a rigorous winter

Although British English has rigour vs. American English rigor, rigorous is spelled thus in all varieties of English.

• (showing, causing, or favoring rigour/rigor): painstaking, scrupulous; see also Thesaurus:meticulous
• (severe; intense): harsh, strict; see also Thesaurus:stern

• (antonym(s) of “severe; intense”): arbitrary, capricious, whimsical

• nonrigorous
• overrigorous
• rigorously
• rigorousness
• unrigorous

• “rigorous”, in OneLook Dictionary Search.
• William Dwight Whitney, Benjamin E[li] Smith, editors (1911), “rigorous”, in The Century Dictionary[…], New York, N.Y.: The Century Co., →OCLC.