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supercalifragilisticexpialidocious

[soo-per-kal-uh-fraj-uh-lis-tik-ek-spee-al-i-doh-shuh s]
adjective
  1. (used as a nonsense word by children to express approval or to represent the longest word in English.)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Word Origin and History for supercalifragilisticexpialidocious

from song in 1964 Disney movie version of "Mary Poppins;" subject of a lawsuit based on earlier song title "Supercalafajalistickexpialadojus" (1949), but other versions of the word also were in circulation.

Online Etymology Dictionary, © 2010 Douglas Harper