Cromulent is, well, a perfectly cromulent word. Cromulent means acceptable, fine, or typical in use. However, this one has probably escaped you unless you are a Simpsons fan. It was added to the Webster’s dictionary in September 2023.
The show’s writers challenged themselves to invent a word or two that sounded legitimate and might be in use. In the show, one of the students remarks that they have never heard of the word “embiggen,” to which the teachers reply, “I don’t know why,” “It’s a perfectly cromulent word.”
The joke was on the audience since both words were fictitious. The writer David X. Cohen is given credit for “cromulent.”
But fictitious words have a way of “noodling” their way into everyday speech. Cromulent began to be repeated in online posts, chat rooms, and the like until it was accepted.
Firstly, in our opinion, “firstly” is not a recommended word because it is misused more than correctly used. There are few, if any, sentences where first cannot be used in place of firstly. It is shorter and read and spoken more easily.
It is no more correct to say, “Firstly, gather all the pencils up and put them in the drawer.” than to say, “First, gather all the pencils up and put them in the drawer.”
Webster’s lists synonyms for firstly, as initially, originally, and primarily. All of these would be preferable and seem to us to be grammatically superior.
Technically, very technically, they are both words, and both pass a grammar test. But proper grammar begs for simplicity and clarity and, firstly does not pass the test for us.