The Rice University Neologisms Database

Casually or informally. Casually, informally. The word itself is an example of its meaning, due to its slangy nature, and sound symbolism may have had something to do with the coinage, although the word is obviously a clipping of ‘casually.’ A shorter version of the adverb ‘casually’ was easier and quicker to say. The shortness and unconventionality of the new word illustrated casualness and thus symbolized its own meaning.