• Etymology Today from M-W: arduous\AHR-juh-wus\
1 a : hard to accomplish or achieve : difficult *b: marked by great labor or effort : strenuous
2 : hard to climb : steep

"To forgive is the most arduous pitch human nature can arrive at." When Richard Steele published that line in The Guardian in 1709, he was using "arduous" in what was apparently a fairly new way for English writers in his day: to imply that something was steep or lofty as well as difficult. Steele's use is one of the earliest documented in English for that meaning, but he didn't commit it to paper until almost 200 years after the first uses of the word in its "hard to accomplish" sense. Although the "difficult" sense is older, the "steep" sense is very true to the word's origins; "arduous" derives from the Latin "arduus," which means "high" or "steep."

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