What part of speech is "why"?

To determine the part of speech of "why",we need to know the types of parts of speech.Remember that there are eight types of parts of speech in English language.


The eight types of  parts of speech are noun,pronoun,verb,adverb,preposition, conjunction and interjection.Remember that determiners are a special type of adjective.

To find out the part of  speech of "why",we need to  remember that a single word in different sentences can functions as different parts of speech.



Now analyse the following example:

●Why did  he do it?


Explain:Here "why"is modifying the verb "do".We know that only adverb can modify a verb.So the part of speech of why is an adverb here.Observe the following example:


●He did it for that reason.

●Why did he do it?


Now read the explanation below:

●He did it for that reason.


We know that did is here an transitive verb.So "did" will  have a object here.A object sits after a verb without any preposition before it.Here"it" is a object of the verb" did".


●He did it for that reason

Sometimes a noun becomes an adverb with the help of a preposition.To be a preposition,a part of speech must have a noun or noun phrase after it.

●He did it for that reason.

Here "that reason" is a noun phrase and functioning  as the object of "for"."for that reason" is a prepositional phrase from the structural side but it is functioning as an adverb here as it is modifying the verb "did"(why did=for that reason)


●He did it for that reason

●Why did he do it?

●Why=for that reason







Now consider the following example:


●I know the reason why you did it.




Explanation:


Structure of a clause:

●Sub.+Finite verb+Extension.

●Clause+Conjunction+Clause

A conjunction can join two clauses.

●I know the reason why you did it.

●Clause=I know the reason


 ●Clause=you did it.

◆Clause +why+clause


●I know the reason why you did it.

Here "why" is connecting two clauses together.So,the part of speech of" why" is a conjunction here.





Now analyse the following example:


◆Rahim wants to know the whys and wherefores.




Here"why" is used as the object of the verb " know".We know that an object may be a noun or pronoun.


Structure of Noun Phrase:


●Determiner+Noun

=the +whys

(Plural of why is whys)

=the+wherefores


●Rahim wants to know the whys and wherefores.

Here the part of speech of why is a noun.





Now read the following example:


●Why,that is nothing but common vegetable soup.

Here "why" is a interjection because it is expressing the surprise of mind.

Conclusion:We are getting four  parts of speech for "why":adverb, conjunction   noun and interjection)