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 "Macavity: The Mystery Cat":
Macavity’s a Mystery Cat: he’s called the Hidden Paw —
For he’s the master criminal who can defy the Law.
He’s the bafflement of Scotland Yard, the Flying Squad’s despair:
For when they reach the scene of crime — Macavity’s not there!
 
Macavity, Macavity, there’s no one like Macavity,
He’s broken every human law, he breaks the law of gravity.
His powers of levitation would make a fakir stare,
And when you reach the scene of crime — Macavity’s not there!
You may seek him in the basement, you may look up in the air —
But I tell you once and once again, Macavity’s not there!
 
Macavity’s a ginger cat, he’s very tall and thin;
You would know him if you saw him, for his eyes are sunken in.
His brow is deeply lined with thought, his head is highly domed;
His coat is dusty from neglect, his whiskers are uncombed.
He sways his head from side to side, with movements like a snake;
And when you think he’s half asleep, he’s always wide awake.
 
Macavity, Macavity, there’s no one like Macavity,
For he’s a fiend in feline shape, a monster of depravity.
You may meet him in a by-street, you may see him in the square —
But when a crime’s discovered, then Macavity’s not there!
The phrase "Macavity, Macavity" is a example of epizeuxis
    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.