abbreviations: acronyms and initialisms

Acronyms and initialisms are both types of abbreviations that are formed from the first letters of a group of words, without spaces (and usually without periods).

On this page

• Pronunciation
• Capitalization
  • Exceptions
• Redundancy
• Articles
  • Acronyms
  • Initialisms

Pronunciation

Although they are formed the same way, acronyms and initialisms are pronounced differently.

An acronym is pronounced as a word:

• NAFTA  (North American Free Trade Agreement; pronounced naff-ta)
• NATO (North Atlantic Treaty Organization; pronounced nay-toe)
• UNICEF (United Nations International Children’s Emergency Fund; pronounced u-ni-seff)

In an initialism, each letter is pronounced separately or sounded out:

• CBC (Canadian Broadcasting Company; pronounced see-bee-see)
• RCMP (Royal Canadian Mounted Police; pronounced are-see-em-pea)
• UFO (Unidentified Flying Object; pronounced u-eff-oh)

Capitalization

As a general rule, use upper-case letters for acronyms or initialisms in their entirety, even if some of the component words or their parts are not normally capitalized (unless the organization concerned prefers lower case):

• CAA (Canadian Automobile Association)
• OSSTF (Ontario Secondary School Teachers’ Federation)
• FORTRAN (formula translation)
• CISTI (Canada Institute for Scientific and Technical Information)

Exceptions

One exception to the above rule occurs in the case of common-noun acronyms treated as full-fledged words; these are written entirely in lower case without periods:

• radar
• laser
• scuba
• snafu

A second exception involves acronyms of company names that are formed from more than the initial letters of the words they represent. Usually, in that case, only the first letter of the acronym is capitalized:

• Cameco (Canadian Mining and Energy Corporation)
• Corel (Cowpland Research Laboratory)
• Nabisco (National Biscuit Company)

Redundancy

When using acronyms or initialisms that include an abbreviation for number, do not repeat the word number after the abbreviation. Either write the expression out in full, or use the abbreviated form on its own.

• social insurance number or SIN (not SIN number)
• personal identification number or PIN (not PIN number)
• International Standard Book Number or ISBN (not ISBN number)

Articles (the, a/an)

The rules concerning the use of an article before the abbreviation are different for acronyms and initialisms.

Acronyms

Usually, an article is not used before an acronym:

• The members of NATO (not the NATO) rejected the idea.
• Children often collect for UNICEF (not the UNICEF) at Halloween.
• NAFTA (not The NAFTA) came into effect in 1994.

However, if the acronym is used as a modifier, it may be preceded by the definite or indefinite article:

• the NATO recommendation
• a UNICEF donation box
• a NAFTA Certificate of Origin

When the indefinite article is used before an acronym, the choice of form (a or an) depends on pronunciation, not on spelling; in other words, use a if the acronym begins with a consonant sound, and an if it begins with a vowel sound:

• a NATO decision (a before the consonant sound n)
• a UNICEF project (a before the consonant sound y, as in you)
• an ACTRA award (an before the vowel sound ă)

Initialisms

The definite article is used before many initialisms (including those representing the name of an organization):

• The RCMP investigated the crime.
• A private member’s bill was introduced by the MP for my riding.
• John brought the CD back to the store.

But the definite article is omitted before an initialism representing a substance, method or condition:

• A ban has been called for on products containing TCEP (not the TCEP).
• Ayesha is taking a course in CPR (not the CPR).
• A child with ADHD (not the ADHD) can benefit from behaviour management techniques.

In the case of the indefinite article, since initialisms are abbreviations pronounced letter by letter, you must go by the pronunciation of the first letter when choosing whether to use a or an.

If the first letter begins with a consonant sound when pronounced, then choose the article a:

• a CBC production (C starts with the sound s as in see)
• a PhD candidate (P starts with the sound p as in pea)
• a UN spokesperson (U starts with the sound y as in you)

a YMCA (Y starts with the sound w as in why)

But if the first letter in the initialism starts with a vowel sound when pronounced, then choose the article an:

• an FM station (F starts with the sound ĕ as in eff)
• an HIV treatment (H starts with the sound ā as in aitch)
• an MP (M starts with the sound ĕ as in em)
• an RCMP officer (R starts with the sound ä as in ar)