Abbreviation

Initialisms are a form of abbreviation in which a phrase is abbreviated to the first letter of each word in the phrase; familiar examples include

• CPA, for Certified Public Accountant
• CBS, for Columbia Broadcasting System
• KJV, for King James Version.

Initialisms are distinguished from acronyms in that initialisms are pronounced as individual letters, while acronyms are pronounced as if the letters spelled out a word (which they may in some cases do). The use of the word "acronym" to include initialisms is imprecise, but increasingly accepted.

Both initialisms and acronyms are defined by custom; sometimes they do not strictly follow the rule of using every initial, or only the first initial. Unimportant words may be omitted. In the case of acronyms a certain amount of creativity may be employed.

• FBI, for Federal Bureau of Investigation'
• AFL-CIO, for American Federation of Labor and Congress of Industrial Organizations

Examples of acronyms include:

• USA PATRIOT Act, for Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act
• TULIP, for Total Depravity, Unconditional Election, Limited Atonement, Irresistible Grace, and Perseverance of the Saints (the core tenets of Calvinism).
• Roy G. Biv, for Red, Orange, Yellow, Green, Blue, Indigo, and Violet (the conventional description of the colors in the spectrum).