“Roots of the word have been defined, as Richard Lederer writes in his book Crazy English as follows: super- “above,” cali- “beauty,” fragillistic- “delicate,” expeali- “to atone,” and docious- “educable,” with the sum of these parts signifying roughly “Atoning for educatability through delicate beauty.”[citations needed] This explication of its connotations suits the fictional character of Mary Poppins, in that she presents herself as both superlatively beautiful and also supremely intelligent and capable of great achievements.”

“Supercalifragilisticexpialidocious!”

which is a made up word from the musical version of Mary Poppins.

As to the longest word:

The longest word in any of the major English language dictionaries is pneumonoultramicroscopicsilicovolcanoconiosis, a 45-letter word which refers to a lung disease contracted from the inhalation of very fine silicious particles. Research has discovered that this word was originally intended as a hoax. It has since been used in a close approximation of its originally intended meaning, lending at least some degree of validity to its claim.

http://www.digitaltimes.com/kids/lyrics_for_kids/supercalifragilistic.html

extremely, very

like you are supercalifragilisticexpialidocious grateful that we all answered your questions.take care