First and firstly are both ordinal (or ordering) adverbs that English speakers and writers use to enumerate related points (e.g., first…second…third… or firstly…secondly…thirdly…). Because first, second, and third work perfectly well as both adjectives and adverbs, some people find that adding -ly is superfluous and even a little bit pretentious. In other words, it is grammatical overkill.
Is “Firstly” a Real Word?
Dictionary giants Samuel Johnson and Noah Webster did not recognize firstly as a word at all. Surprised? Native English speakers naturally warm to the word firstly as an ordinal adverb because most adverbs end in -ly. Not all adverbs do; consider fast, well, and often, for example.
Johnson and Webster clearly believed that first should be included in this irregular adverb group, and that firstly should never be used at all.
Yet it would be silly to say that firstly isn’t part of the English language. We hear it all the time. The question is this: will using firstly when you enumerate points make your writing seem less correct?
Should I Use “First” or “Firstly?”
It is not wrong to use firstly, secondly, and so on to enumerate your points. Nor is it wrong to use the simpler first, second, etc.
These statements are equivalent in meaning. Nevertheless, there are good reasons for choosing the “first” sequence over the “firstly” sequence.
First, using first is a sure win. If your writing is being published or evaluated, or even if you would like to seem proficient to your coworkers, use the construction that is never criticized rather than the one that is frequently criticized.
Second, the unnecessary -ly may not seem pretentious to you when applied to the lower numbers, but they will, once you follow them logically up the scale. Beyond fourthly and fifthly, they become quite ridiculous. (Seventhly? Eleventhly?)
Third, have you ever noticed that firstly doesn’t have a cognate in the idioms we use every day? You would never say firstly come, firstly served or at firstly glance.
Whichever system you choose, avoid mixing your methods. For example, using firstly then second and third, will simply open you up to more censure, even if there is no hard-and-fast rule to stop you.
When to Use “At First”
At first is not used to enumerate points as first and firstly are.
The phrase at first means “in or at the beginning.”
She denied eating the cookie at first , but she soon understood that the crumbs on her dress had given her away.
I disliked bungee jumping at first , but now I can’t imagine living without it.
If you just can’t get enough of ordinal numbers now that you have learned about first vs. firstly, find out some more about them.