I am not familiar with the idea that an adverb can function as a conjunction at the same time. Here are a couple of sentences that are confusing me.

This is the reason why she left him.


He was transferred to New York, where he was promoted to a higher level.

The relative adverbs why, where, when, and how seem to introduce a clause. Therefore, can they also be called conjunctions? If yes, would I be right in assuming that relative adverbs can function as conjunctions at the same time?

3 Answers 3


श्री गणेशाय नमः

The problem here is that parts of speech (adverb, conjunction, pronoun, etc.) are being used as labels to classify words as "being" one and only one part of speech, and that this categorization seems to be directed by faulty definitions.

Parts of speech are uses of words, and in English almost any word can be used in a number of such ways. Definitions of such use categories are just summaries, and not directions to be followed.

So, first of all, it is entirely possible for any English word to "be" more than one part of speech, depending on the context that word appears in.

In this case, the wh-words that have adverbial meanings
      (temporal: when; locative: where; purpose/cause: why; manner/means: how)
are indeed used to introduce clauses, like many adverbs; but this doesn't make them conjunctions.

Conjunctions are one special class of words with special grammar.
When, where, why, and how belong, however, to a different special class of words, with equally special grammar. In fact, they constitute one subclass of this special class.

Most of the other wh-words (what, which, who) refer to nouns, so they're called pronouns --
   either interrogative pronouns (because they're used to introduce question clauses)
   or relative pronouns (because they're also used to introduce relative clauses).

Second, then, it's quite common for something other than a conjunction to "introduce clauses". Complementizers introduce complement clauses (including embedded wh-question complements), adverbs introduce adverbial clauses, etc. The traditional definitions don't go nearly far enough; they're rough guides, no more.

These are also the proper terms for the wh-words with adverbial senses. They came originally from Indo-European oblique noun cases like Locative and Instrumental, and they were used in much the same way as any other interrogative or relative pronoun, to introduce clauses.

Since they don't refer to nouns, however, clauses that they introduce have adverbial restrictions.

Relative clauses, for instance, must modify a noun, but if the relative pronoun is where, the noun it modifies has to be place, or a synonym, or some other word that refers to a place. Similarly, relatives headed by when must modify nouns referring to a point or length of time; the time when itself is most common.

Why and how are even more restricted.
How itself cannot be used at all as a relative pronoun, even if it's modifying the right noun:

  • I don't like how he did that.
  • I don't like the way he did that.
    but not
  • *I don't like the way how he did that.

Why relative clauses must modify the noun reason. Synonyms don't work.

  • I'm unclear on the reason why he did that.
  • *I'm unclear on the purpose why he did that.
  • *I'm unclear on the intention why he did that.

Essentially, the phrase the reason why has become frozen.
There's a lot more, but I forbear.

  • 1
    Mr. Lawler, excellent answer. But I am intrigued by your mention of "श्री गणेशाय नमः" which is a Sanskrit mantra said in praise of Lord Ganesha, one of the Hindu deities. How are you aware of this Sanskrit phrase? I am curious. Commented Apr 9, 2014 at 17:06
  • 5
    Linguists (i.e, grammarians) often study Sanskrit as part of our training; the science of phonetics, as well as the science of grammar, were after all invented by Pāṇini. And I was recently reminded that Sri Ganesh is the patron of grammarians. Commented Apr 9, 2014 at 17:56
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    It's a very different kind of language from English. It's heavily inflected, whereas English has almost no inflection. No language is "logically perfect"; logic is just a stick-figure representation of some parts of language -- not the other way around. Language is alive, part of the human species, but logic is just a form of mathematics, made up by humans. Commented Apr 9, 2014 at 18:54
  • 2
    If it's always the same word, yes it's repetitive, and that's why words get deleted. Commented May 3, 2020 at 21:48
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    @JohnLawler: Excellent description!
    – Ram Pillai
    Commented May 16, 2020 at 17:07

Generally question words can be used for relative clauses and for subordinated question clauses:

1 Where have you found it?

2 the place where I found it

3 He asked me where I had found it.


Subordinating Conjunctions vs. Relative Pronouns & Relative Adverbs.

A subordinate or depending clause is joined with a main clause by : (1) subordinating conjunctions and (2) relative pronouns/adverbs.

It must be noted that relative pronouns/adverbs and subordinating conjunctions are different even though both of them introduce a depending clause.

Relative pronouns act as the subject/object of the dependent clause. Relative adverbs modify the verb of the dependent clause. At the same time, both the relative pronouns and relative adverbs qualify the antecedents (a noun or a pronoun in the main clause) :

Relative pronouns : who, whom, whose, which, that..

This is the boy who stood first in the exam. Relative pronouns (who) is the subject of the depending clause and qualifies its antecedent "the boy" in the main clause.

Relative adverbs : When, Where, Why. Adverbial meanings of the relative adverbs : When >> temporal, Where >> locative, Why >> cause/purpose "I know the time when he went there." "I know the place where he lives." "I know the reason why he went there." Here, the relative adverbs, 'when', 'where' and 'why' modify the verbs of the depending clause and qualify the antecedents 'the time', 'the place' and 'the reason' respectively.

But "The reason why" is redundant and unnecessary. "The way how" is INCORRECT. How means 'the way'. I know the way he did it. Or, I know how he did it. Here, the subordinate clause is a noun clause, and 'how' acts as a subordinating conjunction.

But subordinating conjunctions are merely followed by the subject of the depending clause. In other words, subordinating conjunctions only introduce the depending clauses. For example, I know that he is honest. You will pass if you study hard. He failed the exam because he was idle. etc.



  • But JL says that the expression 'the reason why' has become frozen. I read that as meaning that essentially, it's a lexeme in which why (not 'which') has lost its individual identity. Trying to shoehorn its usage here into a word class is unhelpful. Commented May 3, 2020 at 18:57
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    But 'I'm unclear on the purpose why he did that.' is ungrammatical. If 'why' is a word that 'modifes the verb of the depending clause and at the same time qualify the antecedent in the matrix clause', why doesn't it work here? (Also, note that ' I know the way how he solved the problem. ' is ungrammatical.) // As a general suggestion on ELU, unless you are way above PhD level in English Language (and preferably even then), it is considered necessary to add attributed linked quotes from recognised authoritative works such as Quirk, Greenbaum et al; Huddleston & Pullum; McCawley. Commented May 4, 2020 at 11:22
  • "The reason why" is redundant and unnecessary. "The way how" is INCORRECT. How means 'the way'. I know the way he did it. Or, I know how he did it. Here, the subordinate clause is a noun clause, and 'how' acts as a subordinating conjunction. Commented May 11, 2020 at 8:07
  • Redundancy doesn't make something wrong Commented May 18, 2020 at 13:36
  • That's an opinion. But authentic grammar books say "The way how" is wrong. Commented May 18, 2020 at 13:59

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