What is a 7 letter adverb?

There are no 7-letter adverbs in the English language. The longest adverbs are typically 6 letters, like "slowly" and "quickly."

It's possible you're thinking of a word that is not strictly an adverb, but could function as one in a specific context. Or perhaps you've come across a made-up word.

Can you provide more information about the context or the word you're thinking of?