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el·lip·sis əˈlipsis/ noun the omission from speech or writing of a
word or words that are superfluous or able to be understood from
contextual clues. a set of dots indicating an ellipsis. Google Dictionary
Words for you to fill in because you may have a different answer:
Everyone loves pie. The best pie in the world is... (you 'fill-in' your
favourite flavour.)
Words that are not necessary but were a part of the phrase quoted: ... served with a side of humble pie." The [...] says the entire sentence wasn't quoted because it was unnecessary for the reader to understand.
The sentence could have read, "When I finally understood that I had been haughty,
the minister admonished me and served me with a side of humble pie."
We did not need to know about the minister to understand the part you
quoted.
Humble Pie is as stated simply an idiom for recognising that you made an error and that you feel sorrow over it. You are humbled by your error.