Sentence:  Some <WSD>alphabetisms</WSD> are written as if they weren't <WSD>alphabetisms</WSD> at all, like "deejay" for "DJ", "disc jockey", or "emcee" for "MC", master of ceremonies. 
Meaning of the word marked with <WSD> tags:  An initialism: an abbreviation which is read letter by letter, such as (UN).