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Abbreviations are shortened forms of words or phrases. Because they may not be understood by all users, they allow for misinterpretation. Consequently they are not permitted in fully specified names (FSN). They are not allowed in preferred terms (PT) or synonyms (SYN) unless they are accompanied by the fully expanded term. 


Abbreviations are allowed in FSNs when they are:

  • Part of an official name of an organization or instrument

For example,



Acronyms are a specific type of abbreviation. They are formed from the initial letters of words and may be pronounced as words.

For example, 

    • CT of head is the preferred term for Computed tomography of head (procedure)

Acronyms can be misinterpreted because they are not fully spelled out and have different meanings in different situations. Acronyms are not allowed in FSNs.


An acronym is allowed in an FSN when it has become a word in its own right, i.e. included in dictionaries; understood without expansion to its original full form (e.g. Laser device (physical object) ).

Preferred terms and synonyms

Acronyms are allowed in PTs or SYNs when accompanied by the fully expanded term.

  • Acronyms that stand alone, i.e. have no other text in the description are followed by a space-hyphen-space, then the fully expanded term.

For example,


The first word after the dash should be lower case as per usual capitalization rules.

  • Those that have additional text are to be followed by a space then the expanded form in parentheses. 

For example, 


Only the fully expanded term, not the acronym, should be in parentheses.

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