temerarious [tem-uh-rair-ee-uhs]
adjective:
marked by temerity : rashly or presumptuously daring; recklessly bold
Examples:
Year by year Formula 2 provides excellent show for the fans. The drivers are determined and temerarious, the cars are fast and fight is tight. (Jim Perrin, Racing with tough guys: what is special about Formula 2 in Baku, Azernews, June 2017)
The day was one of tense expectation, when everyone lived from hour to hour for the next bulletin. Radio sets worked overtime; constructive plans were impossible and there was a certain amount of diffidence as to who would make the first sign that the great moment had arrived, until temerarious tradesmen began to make a display of flags and national colours in their windows. (Stacia Briggs, How East Anglia celebrated VE Day, Eastern Daily Press, May 2020)
The Master of the Horse was a young officer of a brave and even temerarious disposition. (Robert Louis Stevenson, New Arabian Nights)
That may have been temerarious, since building material of perfect quality is required when chances are taken. (Elizabeth Boyle O'Reilly, How France Built Her Cathedrals)
Origin:
'rash, reckless,' 1530s, from Latin temerarius 'rash, heedless, thoughtless, indiscreet,' from temere 'blindly, rashly, by chance' (Online Etymology Dictionary)
If you have guessed that temerarious may be related to the somewhat more common word temerity, you are correct. Temerarious was borrowed into English in the early 16th century from Latin temerarius, which in turn derives from Latin temere, meaning 'blindly' or 'recklessly'. Temerity, which arrived in English over a century earlier, also derives from temere; another descendant is the rare word intemerate, meaning 'pure' or 'undefiled'. Temere itself is akin to Old High German demar, Latin tenebrae, and Sanskrit tamas, all of which have associations with darkness. (Merriam-Webster)