Here's why:
* Interjections express sudden emotion or feeling: They are single words or short phrases that stand alone, not part of a sentence structure.
* Plurality implies multiple items: Interjections are singular in nature because they express a single, sudden feeling.
Examples:
* Singular: "Ouch!" "Wow!" "Hey!"
* Not Plural: *Not "Ouchs!"* *Not "Wows!"* *Not "Heys!"*
However, there are exceptions:
* Repetition for emphasis: You might hear someone say "Ouch! Ouch!" to emphasize the pain. This isn't technically a plural, but a repetition for effect.
* Certain interjections are inherently plural: Words like "Hurrah!" or "Bravo!" can be seen as expressing multiple voices or a general shared feeling.
In general, interjections are not pluralized. They are meant to capture a sudden and single moment of emotion.