extremely
adv.to a very high degree. You use this to make an adjective or another adverb much stronger.
adv.to a very great degree or extent. Used as an intensifier to emphasize the quality of the word it modifies.
“The weather is extremely hot today.”
“The team worked extremely hard to finish the project before the midnight deadline.”
“While the initial results were promising, the researchers remained extremely cautious about drawing any final conclusions until the second phase of the study was complete.”
Typically placed immediately before the adjective or adverb it modifies.
As an adverb of degree, it must modify an adjective or adverb, not a noun directly.
Usage extremely difficult · extremely high · extremely small
From extreme + -ly.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.