An interjection is a word or short phrase that expresses a sudden feeling or reaction, such as surprise, pain, joy or hesitation: Wow! Ouch! Oops! Hmm. As Oxford Learner's Dictionaries defines it, an interjection is one of the eight traditional parts of speech, but it is unique because it stands grammatically apart from the rest of the sentence. You can usually remove an interjection without breaking the sentence, since it carries emotion rather than information.
Interjections are most common in spoken English, dialogue and informal writing. They make language sound natural and human, but they are rare in formal essays and reports. Learning the main types and how to punctuate them will make your conversation and creative writing far more lively and authentic.
Types of Interjection
Interjections fall into several groups depending on the feeling or function they carry.
| Type | Examples | Use |
|---|---|---|
| Emotion | wow, yay, ugh, yuck | joy, disgust, excitement |
| Pain | ouch, ow, argh | sudden hurt |
| Surprise | oh, oh no, gosh, whoa | shock or astonishment |
| Greeting | hi, hey, hello, bye | opening or closing contact |
| Hesitation (filler) | um, er, hmm, well | thinking time |
| Agreement | yes, yeah, uh-huh, okay | confirming |
How to Punctuate Interjections
An interjection's punctuation depends on how strong the feeling is and where the word sits.
| Strength | Punctuation | Example |
|---|---|---|
| Strong feeling | exclamation mark | Wow! That's amazing. |
| Mild feeling | comma | Well, I suppose so. |
| Inside a sentence | set off by commas | It is, oh, about three miles. |
The removal test: if you can delete a word and the sentence still works grammatically, it is probably an interjection. Oh, I forgot my keys still works as I forgot my keys. The interjection only adds the emotion of realisation.
Interjections vs Other Words
Some words can be interjections in one sentence and a different part of speech in another:
- Well! (interjection of surprise) vs She sings well. (adverb)
- Oh, really? (interjection) vs the noun O in poetry.
- Yes can be an interjection (Yes!) or a one-word answer.
Register: When to Use Them
Interjections belong to informal and spoken English. They are perfect for dialogue, texts, stories and casual speech, but you should avoid them in academic essays, business reports and exam writing, where they sound out of place. Knowing this difference in register is part of using interjections well.
Common Mistakes
- Overusing exclamation marks: reserve them for genuinely strong feeling.
- No punctuation: an interjection needs a comma or exclamation mark to separate it.
- Wrong register: avoid wow or oops in formal writing.
- Confusing oh and o: use oh for interjections; O is rare and poetic.
Practice Exercises
Grammar Quiz
Identify the interjection in each sentence.
Cloze Dropdown
Choose the interjection that fits each emotion.
Complete the Sentence
Add an interjection with the right punctuation.
Matching Pairs
Match interjections with the feelings they show.
Unjumble
Reorder words into a sentence with an interjection.
Flash Cards
Drill interjections and their meanings.
Master English Parts of Speech
LexFizz has 30 free interactive exercises — no sign-up needed. Start practising interjections today.
Browse All Exercises →Explore related grammar topics:
Frequently Asked Questions
What is an interjection?
An interjection is a short word or phrase that expresses sudden emotion or reaction, such as Wow! Ouch! Oh no! It is one of the eight parts of speech and stands grammatically apart, so you can usually remove it without breaking the sentence.
What are some common interjections?
Common interjections include oh, wow, ouch, oops, ugh, yay, hmm, well, hey and yes. They cover feelings like surprise, pain, disgust and joy, as well as functions like greeting, hesitation and agreement.
How do you punctuate an interjection?
Use an exclamation mark for strong feeling (Wow!) and a comma for mild feeling (Well, I suppose so). An interjection inside a sentence is set off by commas: It is, oh, about three miles away.
What are the main types of interjection?
The main types express emotion (wow, ugh), pain (ouch, ow), surprise (oh, whoa), greeting (hi, bye), hesitation or filler (um, er, hmm) and agreement (yes, uh-huh). Each adds feeling or manages the flow of conversation.
Can I use interjections in formal writing?
Generally no. Interjections belong to informal and spoken English, so they suit dialogue, stories and casual messages. In academic essays, business reports and exam writing they sound out of place, so avoid them in those contexts.
Is an interjection a real part of speech?
Yes. Interjection is one of the eight traditional parts of speech, alongside nouns, verbs and adjectives. It is unusual because it does not connect grammatically to the rest of the sentence and exists mainly to convey emotion.
What is the difference between well as an interjection and an adverb?
Well is an interjection when it expresses hesitation or reaction (Well, I'm not sure) and an adverb when it describes how something is done (She sings well). The same word can belong to different parts of speech depending on use.
Are um and er interjections?
Yes. Um, er and hmm are filler interjections that signal hesitation while a speaker thinks. They are natural in speech but should be removed from written work, as they add no meaning on the page.
Do interjections change form?
No. Interjections never change for tense, number or person. Wow is always wow. This invariability is one feature that sets them apart from nouns and verbs, which take endings such as -s or -ed.
Can a phrase be an interjection?
Yes. Short fixed phrases can act as interjections: oh no, oh dear, my goodness, good grief and no way. They function exactly like single-word interjections, expressing emotion and standing apart from the sentence grammar.