A definition has one of the following two forms:

1. 

   

   :
   • The definition is complete. It contains

     

     that represent the full set of necessary and sufficient conditions.

2. 

   

   :
   • The definition is incomplete. It contains

     

     that represent a set of necessary conditions but this set of conditions is not sufficient to fully define the

     

Note: A necessary condition is a characteristic that is always true of a

Example: |morphology| = |fracture| is a necessary condition of |fracture of femur|

Note: If all members of a sufficient set of conditions are true they imply that the is also true.

Example: |morphology| = |fracture| and |finding site| = |bone structure of femur| form a sufficient set of conditions that define the |fracture of femur|

Note: All members of the set of sufficient conditions are also necessary conditions. However, some necessary conditions may not form part of the sufficient set of conditions.

Example:

Consider the |gastric ulcer|

• The

  |finding site|

  =

  |gastric mucosa|

  is a necessary condition for

  |gastric ulcer|

  :
  • This is true because all gastric ulcers necessarily involve the

    |gastric mucosa|

• The definition

  |morphology|

  =

  |ulcer|

  and

  |finding site|

  =

  |stomach structure|

  is a sufficient definition for

  |gastric ulcer|

  :
  • This is true because any ulcer in a stomach structure is a

    |gastric ulcer|

• Therefore, an assertion that a person has an

  |ulcer|

  with

  |finding site|

  |stomach|

  is sufficient to imply that they have a

  |gastric ulcer|

  :
  • Since a gastric ulcer necessarily involves the

    |gastric mucosa|

    it should be possible to deduce that a person with an "ulcer" with finding site

    |stomach|

    has a disorder of with a site

    |gastric mucosa|

Sufficient definitions

A sufficient definition consists of a set of defining (and relationshipGroup (field) ) which taken together imply a particular meaning.

The value of a sufficient definition is that it allows post coordinated that is sufficient to define a to be recognized as equivalent to (or a of) a defined

For example:

Gastric ulcer is defined as follows and this is a sufficient definition because any |ulcer| in a |stomach structure| is by definition a |gastric ulcer|

116680003 |is a| = 64572001 |disease| { 116676008 |associated morphology| = 56208002 |ulcer| , 363698007 |finding site| = 69695003 |stomach structure| }

Based on this definition:

Any that specified a disease involving an |ulcer| with |finding site| |stomach| would be equivalent to or a of |gastric ulcer|

However, a query for all disorders involving |gastric mucosa| would incorrectly exclude the |gastric ulcer| as the site is not specified as some stomach structure rather then specifically identifying the gastric mucosa.