What is the proper way to write this sentence:
That feeling came and went relatively quickly.
I cannot figure out if it should say “relatively quickly,” “relatively quick,” or what. Help would be appreciated!
Either one works. You do need an adverb there and you generally look for an ‘-ly’ word for an adverb, but many one-syllable adjectives may also be adverbs – quick, slow, and fast are all either adjectives or adverbs depending on how they’re used.
According to the Oxford dictionary of American style and usage, the best answer is “quickly”. Regardless of which you choose, you do need an adverb there (rather than an adjective), because you’re modifying “relatively”. The other answerer was right: there are some adverbs that don’t end in “-ly”, but most of them do. So why is it “quickly”?
Both “quick” and “quickly” can be used as adverbs, but it has been standard to use “quickly” for about a century. There are a few phrases that still use “quick” as an adverb, though now they’re almost cliches: “get-rich-quick scheme”, or “Come quick!”. These days, “quickly” is the best choice. If one were to use “quick”, it would be grammatically correct, but considered loose or slightly informal.