Abbreviation, Acronym, and Initialism

There is a fine distinction between these words that some consider nitpicking. Abbreviation is the umbrella term for any shortened or contracted form of a word or phrase, such as Dr. for Doctor or lb. for pound. Terms such as FBI, HMO, and NAACP, although widely called acronyms, are actually initialism. The difference is in how they are spoken. An initialism is pronounced letter by letter. An acronym is pronounced as if it were a word. The abbreviation FBI is pronounced "eff-bee-eye." The acronym NASA is pronounced "Nassa."

Please see our post Abbreviations vs. Acronyms vs. Initialisms, which provides more discussion and helpful examples.