"Checkin" Is Not a Verb

Despite what many people --mostly in the computer field-- think, "checkin" is not a verb. It's simply not. Whether or not "checkin" is a word at all may spark a debate in some circles, but assuming it is then it may act as many parts of speech, but not as a verb.

I will repeat the important part for clarity: "checkin" is not a verb. It's simply not.

This site is dedicated to educating people about the common misuses of words like "checkin." It is meant for both non-native speakers who may not know any better, and for native speakers who should know better but don't. It is in no way a substitute for a real education. Poor grammar is an excellent way to make any presentation sound stupid --or program look sloppy-- so if you intend to use this language much then it behooves you to learn it properly.

For clarity, I need to point out that this has nothing to do with verbification, or "verbing." It is completely natural for nouns to become verbs and verbs to become nouns; the problem this site addresses is the manner in which that happens for a particular category of word or phrase. This is not an attempt to arrest the evolution of the language, but to correct mistakes.

About Verbs

Conjugation

It is possible to conjugate verbs. They can change tense and mood. They can change number and person. You will see how even basic conjugation fails for "checkin."

Verb: "Conjugate"

Here are some examples with the verb "conjugate." If you doubt that "conjugate" is a verb (or need to look up what it means), definitions from dictionary.com and Merriam-Webster agree. Note that, as with many verbs, noun forms exist. Here we're using the verb form.

	Singular		Plural
Person	Pronoun	Verb	Pronoun	Verb
1^st	I	conjugate	we	conjugate
2^nd	you	conjugate	you [all]	conjugate
3^rd	he/she/it	conjugates	they	conjugate

Conjgate is a regular verb, so the present tense is simple. Consider the past tense:

	Singular		Plural
Person	Pronoun	Verb	Pronoun	Verb
1^st	I	conjugated	we	conjugated
2^nd	you	conjugated	you [all]	conjugated
3^rd	he/she/it	conjugated	they	conjugated

The past tense is easy to form with a weak verb like "conjugate." This is normal behavior for a verb. English has more complicated verbs, like irregular and strong verbs, but those are generally the oldest verbs in the language. New verbs are regular and weak.

Verb: "Checkin" (?)

As a new verb, "checkin" should follow the regular, weak model that "conjugate" exemplifies. Unfortunately, it does not:

	Singular		Plural
Person	Pronoun	Verb	Pronoun	Verb
1^st	I	checkin	we	checkin
2^nd	you	checkin	you [all]	checkin
3^rd	he/she/it	checkins	they	checkin

Notice the problem with the third person singular. However, let's choose to ignore this problem for now. After all, we can't let one little conjugation problem make thousands of programmers and technical writers look like fools. Plowing right ahead, we'll look at the past tense:

	Singular		Plural
Person	Pronoun	Verb	Pronoun	Verb
1^st	I	checkined	we	checkined
2^nd	you	checkined	you [all]	checkined
3^rd	he/she/it	checkined	they	checkined

Unfortunately, not a single one of those sounds right. It seems that "checkin" can't change tense or conjugate like a normal verb.

A Strong Verb?

Many older verbs are strong verbs, meaning they change tense by modifying an internal vowel or diphthong. As you will see, it doesn't behave like a strong verb, either. Compare the above behavior to the strong verb "sing:"

Present		Past
I sing		I sang
I run		I ran
I meet		I met

See how the strong verb forms its past participle by changing an internal vowel (instead of adding "ed" at the end, for example). "Checkin" does not do that, so it's not a strong verb.

A Separate Verb?

Some grammarians will call this a "phrasal" or "two-part" verb, but this is mostly because some grammarians are seeking tenure at their university posts and must publish anything they can to get or keep that coveted teaching spot. Similar motivation has created definitions for "compound verbs" and "stretched verbs" --all different kinds of verbs, supposedly. Essentially, though, a two-part verb must have two parts and checkin only has one. The following list of checkin's component parts demonstrates this fact.

Part 1: checkin
Part 2:

Having only one part, checkin cannot be a two-part verb.

True Behavior

Someone may make the case that it is irregular. By definition, irregular verbs do not follow rules and have strange conjugations ("I am," "you are," "he is"), but look at how it behaves:

	Singular		Plural
Person	Pronoun	Verb	Pronoun	Verb
1^st	I	check in	we	check in
2^nd	you	check in	you [all]	check in
3^rd	he/she/it	checks in	they	check in

The past tense is also predictable:

	Singular		Plural
Person	Pronoun	Verb	Pronoun	Verb
1^st	I	checked in	we	checked in
2^nd	you	checked in	you [all]	checked in
3^rd	he/she/it	checked in	they	checked in

It appears the verb is "check," which behaves like a regular weak verb (doubling the final consonant is normal: sag => sagged, dip => dipped) in both American and English. The verb form is not a verb at all, but an idiom of a verb and a preposition, like "break down" or "shake up." In fairness to some grammarians, this kind of idiom sometimes has the name "phrasal verb" or "two-part verb." It's true that most idioms of this kind use strong verbs, since they come from Old Norse influence on the language over a thousand years ago. That makes the "check in" idiom unusual, but far more plausible than pretending that we have an irregular verb "checkin" with something like "checkdin" as a past participle. No other verb in the American language behaves that way. Even in the arcane, deprecated predecessor of American (English), no verb behaves that way.

What is it?

As I indicated earlier, I'm sure you can find purists who will argue "checkin" is not a word at all. For the sake of discussion, I will assume it is a word because I do not care one way or another. Let's look at some possibilities:

Adjective

Adjectives describe nouns. Let's put "checkin" with some other adjectives ("stupid" and "alabaster") to see how well they play with each other:

The cat is stupid. It is a stupid cat.
The cat is alabaster. It is an alabaster cat.
The book is checkin. It is a checkin book.

"Checkin" doesn't work well as an adjective.

Adverb

Adverbs are to verbs what adjectives are to nouns. Adverbs describe verbs (or, more accurately, the verb actions). Here are some sentences with adverbs. See if you can tell which does not belong:

The car runs smoothly.
The car runs quietly.
The car runs ~~checkin~~ checkin.

"Checkin" doesn't work well as an adverb.

Noun

Any fourth grader will tell you that a noun is a "person, place, or thing." As such, it is something you can have and something you can modify. Behold as I use my language powers to display ownership of the noun "book" and then modify it:

Owned	I have a book.

Modified	I have a secret book.

I own the book, then make it a secret book. Truly, that is grand. Now I will do the same for "checkin."

Owned	I have a checkin.

Modified	I have a secret checkin.

"Checkin," it seems, works as a noun.

Conclusion

Clearly "checkin" is not a verb. It's simply not. If it is any part of speech at all, it is a noun. While we did not explore every possible part of speech, we saw with certainty that "checkin" is not a verb. It's simply not.

If you take only one thing away from this page, take that one fact: "checkin" is not a verb. Educate others. Correct manuals, software, and web pages as you find them. Tell everyone you know that "checkin" is not a verb. You will make a pedant (me) happy. You will earn the respect of grammar nazis. Most importantly, you will know the truth.

Solutions

Magnanimousness demands that I offer solutions, or correct forms of some of the common abuses of "checkin" Here are some suggestions, assuming you prefer to use "checkin" as a word rather than take a more conservative approach and insist the proper form is "check in" or "check-in."

Common Misuse	Correction
Can you checkin?	Can you check in?
I tried to checkin . . . .	I tried to check in . . . .
Enter your name at the checkin prompt.	(This is acceptable)
Please checkin again.	Please check in again.

What Next

What you do with this information is, of course, your choice. As I mentioned above, however, the ideal choice is to use this knowledge for good and correct errors. The more correct examples people see, the more people will stop believing the lie that this is a verb.

You can also continue your education by learning about other words that are not verbs.

For entertainment you can read a sarcastic rebuttal to the argument that checkin really is a verb and the language simply has evolved.

Thanks to Mark Pettit for the corrections to the "checkout" page.
Thanks to Nathanial Jones for the observation of phrasal verbs.
Thanks to someone whose email I deleted before I could record his name for his suggestion to add a note on prepositions.
Thanks to John Goodman for the correction on "carryout" in the index.
Thanks to several people on MetaFilter for observing I need to clarify that the site is not about "verbing," just about correct use of a word/phrase.
Thanks to Andrew Dunbar for slowdown and splashdown.