Theory:

Epizeuxis is also known as Palilogia or Subjunctio. When a word or two is repeated immediately without any words in between, it is called epizeuxis.
Pronunciation Guide:
Epizeuxis: Epi (as in epic)-- zeux (as in zooks)-- is (as in is)
In most of the cases, the repeated words appear in the same sentence.
According to Cuddon, Epizeuxis is "a figure of speech in which a word or phrase is repeated emphatically to produce a special effect".  It was originally a Greek word which meant ‘fastening together’.
Now, let us look into some of the examples.
 
The following is an extract from a poem called "Teamwork" by Jan Nigro. In the poem, the first line has the word "teamwork" repeated twice. And there are no words in between the 1st word and the 2nd word. This is an example of epizeuxis.
Example:
Teamwork, teamwork,
Together we can make our dream work.
Then we'll share the joy of what we've done,
Teamwork, everyone!
Let us look into one of the classic examples of epizeuxis. The following example is taken from a famous nursery rhyme.
Example:
Row, row, row your boat
Gently down the stream
Merrily merrily, merrily, merrily
Life is but a dream.
The word "row" in the first line and "merrily" in the 3rd line are repeated, and both are examples of epizeuxis.
 
The following is an extract from the poem "Firework Night" by Enid Blyton.
Example:
BANG!
What's that?
Bang-Bang! Oh, Hark,
The guns are shooting in the dark!
Little guns and big ones too,
Bang–bang-bang!
What shall I do?
Mistress, Master, hear me yelp,
I'm out-of-doors, I want your help.
Let me in-oh, LET ME IN
Before those fireworks begin
To shoot again-I can't bear that;
My tail is down, my ears are flat,
I'm trembling here outside the door,
Oh, don't you love me anymore?
The word "Bang" is repeated twice in the 3rd line and thrice in the 6th line respectively. Each set is a case of epizeuxis.
 
Important!
However, if you had noticed, there is a repetition in the 10th line. The phrase "let me in" is also repeated twice and they appear in the same sentence too. However, it is NOT an example of epizeuxis because there is the word "oh" in between. This kind of repetition is called diacope, and that will be covered in the next chapter.
Hence, epizeuxis is a kind of repetition where a word or phrase from the same sentence is repeated immediately, without any words in between.
Epizeuxis used in the poem "A Legend of the Northland":
Away, away  in the Northland,
Where the hours of the day are few,
And the nights are so long in winter
That they cannot sleep them through;
 
Where they harness the swift reindeer
To the sledges, when it snows;
And the children look like bear’s cubs
In their funny, furry clothes:
 
They tell them a curious story —
I don’t believe ’tis true;
And yet you may learn a lesson
If I tell the tale to you.
 
Once, when the good Saint Peter
Lived in the world below,
And walked about it, preaching,
Just as he did, you know,
 
He came to the door of a cottage,
In travelling round the earth,
Where a little woman was making cakes,
And baking them on the hearth;
 
And being faint with fasting,
For the day was almost done,
He asked her, from her store of cakes,
To give him a single one.
 
So she made a very little cake,
But as it baking lay,
She looked at it, and thought it seemed
Too large to give away.
 
Therefore she kneaded another,
And still a smaller one;
But it looked, when she turned it over, 
As large as the first had done.
 
Then she took a tiny scrap of dough,
And rolled and rolled it flat;
And baked it thin as a wafer —
But she couldn’t part with that.
 
For she said, “My cakes that seem too small
When I eat of them myself
Are yet too large to give away.”
So she put them on the shelf.
 
Then good Saint Peter grew angry,
For he was hungry and faint;
And surely such a woman
Was enough to provoke a saint.
 
And he said, “You are far too selfish
To dwell in a human form,
To have both food and shelter,
And fire to keep you warm.
 
Now, you shall build as the birds do,
And shall get your scanty food
By boring, and boring, and boring,
All day in the hard, dry wood.”
 
Then up she went through the chimney,
Never speaking a word,
And out of the top flew a woodpecker,
For she was changed to a bird.
 
She had a scarlet cap on her head,
And that was left the same;
But all the rest of her clothes were burned
Black as a coal in the flame.
 
And every country schoolboy
Has seen her in the wood,
Where she lives in the trees till this very day,
Boring and boring for food.
Thus, the repetition of the word "away" in the line "Away, away in the Northland" is an example of Epizeuxis as the word "away" is repeated immediately without any word in between.
Reference:
  • Cuddon, J.A. A Dictionary of Literary Terms and Literary Theory . West Sussex, Wiley-Blackwell Publication, 2013.
  • National Council of Educational Research and Training (2019). Marigold. Teamwork-Jan Nigro (pp. 21). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.
  • https://wordsforlife.org.uk/activities/row-row-row-your-boat/
  • State Council of Educational Research and Training (2019). Term-1 English Standard-8. Firework Night(pp. 141-144). Published by the Tamil Nadu Textbook and Educational Services Corporation.
  • National Council of Educational Research and Training (2006). Beehive. A Legend of the Northland-Phoebe Cary (pp. 65 - 67). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.