It's a ficticious word that you say when you want to sound precocious or when your tongue tied and need to come up with something impressive.
"George, what do you have to add to Christy's comments about your budget proposal?"

George, sweat visible now above his brow, fidgeted in his seat as he panicked at his obvious loss of words. Then a miracle happened; he opened up his mouth and said, "supercalifragilisticexpialidocious!"

"That's terrific. Rodger make sure George gets the money he's asking for. Wow, just great George. Christy you could learn from him."
by Stuart Mohr August 02, 2006
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Adj. a nonsense word meaning fantastic; also called supercalifragilistic
"It's Supercalafragilisticexpialidocious, even though the sound of it is something quite atrocious, if you say it loud enough you'll always sound precocious, supercalifragilisticexpialidocious!
Umdiddle umdidllei, Umdiddle umdidllei..
by Jordan H. March 26, 2005
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Extraordinarily good; wonderful.
"the only word to characterize Kepler's discoveries was ‘Supercalifragilisticexpialidocious’"
by Sohammie April 04, 2017
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Well your probably wondering WHAT THE HECK IS DAT!? well actually it’s a very long word most of us can’t don’t know how to say but we say it anyway, why? to seem proper.
Oh you have me all Supercalifragilisticexpialidocious!”

Girl what....”
via giphy
by cwallingallbwabz February 28, 2021
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