The Rice University Neologisms Database

Alcohol. Here, the first letter of the word alcohol is being used to refer to the word itself. This could either be considered a drastic form of clipping or a form of initialism in which there is only one initial. The word ‘A’ has no obvious difference in meaning from alcohol, and it is usually used simply as a cool slang term and a more brief way of using the word, particularly in text messages. Another instance of this type of word formation process is the word ‘D’, meaning defense.