It's Merriam-Webster's Word of the Day for August 5th.
Today's word is capricious, spelled C-A-P-R-I-C-I-O-U-S.
Capricious is an adjective.
It's a formal word that describes someone or something governed or characterized by impulsivity or unpredictability.
Here's the word used in a sentence from USA Today.
Tornadoes are among the planet's most fearsome phenomena,
with terrifying and capricious wind speeds measured as high as 300 miles per hour,
and the US sees more than any other country.
The adjective capricious and its close relation, the noun caprice, a synonym of the word whim,
both come via French from the Italian word capriccio, which has disputed origins.
Capriccio originally referred not to a sudden desire, but to a sudden shiver of horror,
and likely comes from the Italian word cappo, meaning head, and ricchio, the word for hedgehog.
The implication was that someone who shuddered in fear or horror was said to have a hedgehog head,
meaning that the person's hair stood on end, like the spines of a hedgehog.
The link between a whim and a shiver of horror is notably tenuous,
though, and a possible link to the Italian word capra,
meaning goat, has also been suggested, given the whimsy goats seem to employ in their gambling.
A full treatment of the disputed etymology can be found in our online dictionary.
Whatever its origins, capriccio came to mean whim or fancy,
which directly relates to its uses today.