“Supercalifragilisticexpialidocious” ( /ˌsuːpərˌkælɨˌfrædʒɨˌlɪstɪkˌɛkspiːˌælɨˈdoʊʃəs/) is a song from the 1964 Disney musical film Mary Poppins. The song was written by the Sherman Brothers, and sung by Julie Andrews and Dick Van Dyke. It also appears in the stage show version. Since Mary Poppins was a period piece set in 1910, period-sounding songs were wanted. “Supercalifragilisticexpialidocious” sounds like contemporary music hall songs “Boiled Beef and Carrots” and “Any Old Iron”
According to Richard M. Sherman, co-writer of the song with his brother, Robert, the word was created by them in two weeks, mostly out of double-talk
The roots of the word have been define as follows: super- “above”, cali- “beauty”, fragilistic- “delicate”, expiali- “to atone”, and docious- “educable”, with the sum of these parts signifying roughly “Atoning for educability through delicate beauty.” Although the word contains recognizable English morphemes, it does not follow the rules of English morphology as a whole. The morpheme -istic is a suffix in English, whereas the morpheme ex- is typically a prefix; so following normal English morphological rules, it would represent two words: supercalifragilistic and expialidocious. The pronunciation also leans towards it being two words since the letter c doesn’t normally sound like a k when followed by an e, an i or a y.
According to the film, it is defined as “something to say when you have nothing to say”