A word doesn’t necessarily belong to a particular part of speech. Depending on how it is used in a sentence, a word can belong to more than one part of speech. For example, word down can be an adverb, a verb, a preposition, or an adjective:
The sun went down at 5:45 PM. [Adverb]
The storm downed several trees. [Verb]
The shop is further down the road. [Preposition]
The team was little down after yesterday’s close loss. [Adjective]
People find it hard to associate question words such as when with any part of speech, as they think that question words are made just to ask questions and do nothing else in a sentence. But, like down, they function as quite a few parts of speech.
In this post, we’ll analyze the word when grammatically, looking at the four parts of speech it belongs to: adverb (two types), conjunction, noun, and pronoun. We’ll also look at few parts of speech it doesn’t belong to, but few erroneously think it does. And all this with plenty of examples.
The first section looks at when in its role of asking questions.
1. Is ‘when’ an adverb?
Yes.
It can function as an interrogative adverb: interrogative because it is in the form of a question and adverb because it conveys information about time. If you recall, adverbs convey information about time, place, manner, degree, reason, etc. The most common interrogative adverbs are when, where, why, and how. Examples:
When will you come back?
When is the launch event?
“When did you last see him?” My friend asked.
Note that when can also act as interrogative adverb in sentences where it’s not a question word. This has been covered later (under conjunction or subordinating conjunction subcategory) because it doesn’t belong to the direct question category. Examples:
(Comments that go with examples are in square brackets.)
You never know when an unexpected need might arise. [Comment: The underlined part is a noun clause.]
I don’t know when to speak. [Not a clause]
When can also be used as relative adverb where it’s not a question word. This too has been covered later. Example:
May 12, last year, was the day when I was on top of the world after getting admission to my dream college. [The underlined part is a relative clause.]
In the first section, we looked at when in its role of asking questions. But when can also connect parts of a sentence. Conjunctions, relative pronouns, and prepositions are the most common grammatical tools to connect one part of a sentence to the other. In the next three sections, let’s examine if when belongs to any of these three parts of speech.
2. Is ‘when’ a conjunction or subordinating conjunction?
(Note that subordinating conjunction is a subcategory of conjunction. If a word is subordinating conjunction, it’ll certainly be conjunction.)
Yes and no.
Yes. It functions as a conjunction and subordinating conjunction in adverb clause.
No. It doesn’t function as a conjunction or subordinating conjunction in noun clause.
The answer may have come as a surprise to you. When when introduces a dependent clause and joins it to an independent clause, it is commonly treated as a conjunction or subordinating conjunction. But from grammatical perspective, it is not. Let’s dig this up in detail as there is lot of confusion on this point.
What’s a conjunction?
A conjunction is a part of speech that mainly joins clauses but can also join words or phrases. Whereas coordinating conjunctions join grammatically equal elements, subordinating conjunctions introduce dependent clauses and join them to independent clauses. But to be a conjunction, the word can’t play another grammatical role (noun, pronoun, verb, adjective, adverb, etc.) in the clause it introduces. After all, the very same word in the very same sentence can’t be two different parts of speech. Don’t forget that conjunction is one of the eight parts of speech.
There are three types of dependent clauses: adverb clause, relative clause, and noun clause. Here is a summary of whether the connector (we’ll see if it’s a conjunction or not) plays a grammatical role in the clause it introduces.
- Adverb clause: No connector joining an adverb clause to an independent clause plays a grammatical role in the adverb clause it introduces. Hence, they’re conjunctions. And because they make the clause dependent (or make it subordinate), they can be further subclassified as subordinating conjunctions. Examples: because, since, after, before, while, when, until, etc.
- Relative clause: All connectors joining a relative clause to an independent clause play a grammatical role in the relative clause they introduce. (They play the role of pronoun and adverb, which gives these connectors the name relative pronoun and relative adverb.) Hence, they’re not even conjunctions, let alone coordinating or subordinating.
- Noun clause: The situation is mixed in noun clauses. Some connectors joining a noun clause to an independent clause play a role in the noun clause they introduce and some don’t. Those that don’t play a role (if, whether, and that) are subordinating conjunctions. Others are not.
You can call connectors that are not subordinating conjunctions as subordinators (even though not conjunction, they subordinate the clause they introduce), which would include relative pronouns, relative adverbs, and other connectors (except if, whether, and that) that introduce noun clauses.
With that out of the way, let’s come back to whether when is a conjunction or a subordinating conjunction. Now, when introduces all three types of dependent clauses: adverb clause, relative clause, and noun clause.
Let’s take adverb clause first. Examples:
Don’t write a text or email when you’re angry. [The adverb clause has been underlined.]
When the plane landed, police arrested the man who raised false alarm of a bomb on the plane.
As discussed earlier (see first bullet point under ‘adverb clause’ heading), connectors don’t play a grammatical role in the adverb clause they introduce. Hence, they’re conjunctions. And because they make the clause dependent (or make it subordinate), they can be subclassified as subordinating conjunctions.
Let’s take noun clause now. Examples:
You never know when an unexpected need might arise. [The noun clause has been underlined.]
Researchers aren’t certain about when Megalodon went extinct.
In case of noun clause, when plays the role of interrogative adverb, just like its role in asking direct questions. It’s not surprising because noun clauses are often questions put indirectly. Since when plays a role (adverb) in the clause it introduces, it’s not a conjunction, let alone a subordinating conjunction. You can call it a subordinator or other similar term, which BTW is just an informal term, to denote its role in subordinating the noun clause.
Common error: People mistakenly treat when introducing noun clauses as conjunction or subordinating conjunction. That’s because, in common parlance, the term conjunction is associated with any word that joins two clauses and the term subordinating conjunction with any word that joins a dependent clause to an independent clause. People forget to take into account that it can play another part of speech in the dependent clause, in which case it can’t be a conjunction or subordinating conjunction.
3. Is ‘when’ a relative pronoun?
No.
It’s not a relative pronoun; it’s a relative adverb. The relative adverb when too functions like a relative pronoun in joining one part of a sentence to another by referring to a noun, but it refers to a noun representing time. The adverb part in relative adverb, in fact, emanates from this time aspect. Examples:
May 12, last year, was the day when I was on top of the world after getting admission to my dream college. [The relative clause has been underlined.]
In those two months, when nothing much happened in terms of results, I was dispirited.
Pandemic was the time when our patience and resolve was stretched to the limit.
Note that in all the examples, when refers to a time noun (day, those two months, and time).
Common error: This error is less common than the one in noun clause, but people sometimes call when a subordinating conjunction in its role as introducer of a relative clause. But when, in this role, is a relative adverb.
4. Is ‘when’ a preposition?
No.
Few confuse when with prepositions mainly because both connect two parts of a sentence and both can precede a noun or pronoun. A case in point:
I reached at 6 PM.
I reached when no one had come.
I don’t know when others will come.
In all the three sentences, at and when connect two parts of the sentence and are followed by a noun or noun phrase. If at is a preposition, then why isn’t when.
Looking at only the succeeding noun or noun phrase, though, doesn’t present a holistic picture. This does:
I reached at 6 PM.
I reached when no one had come.
I don’t know when others will come.
In the second sentence, the adverb clause introduced by when works as a unit. In other words, when doesn’t come with just the noun phrase no one but lot more, a clause. Same with the third sentence, where a noun clause works as a unit, and here too when can’t be seen with just the following noun others.
From the above examples, you’d realize that mere presence of a noun or noun phrase after a word doesn’t mean it’s a preposition. Adjectives can be followed by a noun or noun phrase. So can others be. But we’ve to look at the holistic picture.
Bottomline, when is not a preposition. And because it’s not a preposition, it can’t initiate a prepositional phrase.
So far, we’ve looked at role of when in asking questions and connecting parts of a sentence. Let’s now examine the final three pieces.
5. Is ‘when’ a noun?
Yes.
When can sometimes function as a noun. Examples:
We don’t know the when and where of the oath-taking ceremony.
As new fossils are unearthed, paleontologists keep shifting the when of homo sapiens’ arrival on the planet.
6. Is ‘when’ a pronoun?
Yes.
When can sometimes function as a pronoun. Examples:
Till when is the restaurant open?
You’re in this job since when.
I get a chance to present when.
7. Is ‘when’ a verb?
Although rarely, some raise question about when being a verb.
Is it a verb? Not even remotely!
We can break. We can tear. We can snap. We can crack.
But can we when?
When doesn’t do any action. Hence, it’s not a verb.
Another test you can run is to check if when has past, past participle, and present participle forms like verbs do.
Can we’ve the words whenned or whenning, assuming it to be a regular verb?
No. Hence, it’s not a verb.
Few also confuse when with linking verb probably because of its role in linking (or joining) a dependent clause to an independent clause. But it’s not a linking verb. As we saw earlier, when acts as a subordinating conjunction (in case of adverb clauses) or a subordinator (in case of noun clauses) or a relative adverb (in case of adverb clauses) in its role in linking a dependent clause to an independent clause.
Summary
When mainly functions as an adverb (with two flavors) and a subordinating conjunction, but it can play few other roles as well:
When is the launch event? [Interrogative adverb]
I don’t know when is the launch event. [Interrogative adverb in noun clause. It’s not a conjunction or subordinating conjunction introducing the noun clause.]
The launch even had already started when I reached the venue. [Subordinating conjunction in adverb clause]
I don’t know the day when the launch event will be held. [Relative adverb in relative clause]
I don’t know the when and who of the launch event. [Noun]
Till when is the launch event open. [Pronoun]
