Merriam-Webster's Word of the Day for December 30, 2023 is:

arduous • \AHR-juh-wus\  • adjective

Arduous is an adjective used to describe something that is very difficult or strenuous.

// The gorgeous waterfall at the top of the mountain was worth the arduous hike.

See the entry >

Examples:

“And with [hockey player, Patrice] Bergeron now enjoying the retired life after 19 seasons spent with the Bruins, the six-time Selke Trophy winner acknowledged that [Zdeno] Chara has already tried to recruit him for some arduous training.” — Conor Ryan, Boston.com, 21 Nov. 2023

Did you know?

Arduous isn’t the type of word one expects to hear in a folk song—it’s a bit too formal—but strenuous work and difficult journeys are the stuff of many a classic tune. Take “The Wayfaring Stranger,” for an example, a somber song about life’s travails performed by everyone from singer and activist Paul Robeson to country star Emmylou Harris: “I know dark clouds will gather o’er me / I know my pathway’s rough and steep.” Such a lyric gets at the dual literal/figurative nature of arduous, which comes from the Latin adjective arduus, meaning “high,” “steep,” or “difficult.” For quite a while after appearing in English in the mid-1500s, arduous hewed closely to the figurative “strenuous” or “difficult” sense until poet Alexander Pope invoked steepness when he wrote of “those arduous paths they trod” in his 1711 work “An Essay on Criticism.” To pen such a work at the age of 23, and in heroic couplets no less, must have been an arduous challenge indeed, but like the wayfaring stranger seeking a brighter land, Pope had his eyes on the prize.