Grammar Monster
Grammar Monster


The Quick Answer
An abbreviation is a shortened version of a written word or phrase used to replace the original.

(From this page, you can learn about the quirks associated with writing abbreviations.)

Writing Abbreviations

An abbreviation can usually be placed into one of four categories:


An acronym is an abbreviation spoken like a word, e.g., BUPA, NAAFI. Through common usage, a number of acronyms have become words in their own rights.

Good examples are sonar, radar, laser, and scuba. (Nowadays, these are rarely capitalized.)

Some acronyms have not yet made a full transition to "recognized word" and can be written with all capital letters or just an initial capital letter, e.g., NATO or Nato.


A contraction is an abbreviated version of a word or words. There are two main kinds:

Initial Abbreviation (or Initialism)

Initialisms tend to be written with capital letters with each pronounced. For example:
  • BBC
  • CNN
  • LRS
These can be written with or without full stops (periods ), but a writer should be consistent throughout a document.

However, when using company names, it is a common convention to copy the company's version. (For example, do not write B.U.P.A. - this company does not use full stops in its own correspondence.)

Syllabic Abbreviation

Syllabic abbreviations are not common. (They are classified as initialisms, and some sources classify them as acronyms, which are abbreviations spoken like words.) They use the initial syllables from multiple words. For example:
  • Kombat (Komandir Batal'ona)
  • Gestapo (Geheime Staats Polizei)
  • Comintern (Communist International)
Top Tip

Writing Scientific Units

When using units such as mph or cm, you can either use a space after the number or not. The choice is yours. However, be consistent throughout your document.
  • 700mph, 99m, 10cm, -4°C
  • 700 mph, 99 m, 10 cm, -4 °C

Be Consistent

There are many different conventions relating to abbreviations. Therefore, the golden rule is simply:

"Pick a style you like and be consistent".