gml:Definition 

The basic gml:Definition element specifies a definition, which can be included in or referenced by a dictionary. 
The content model for a generic definition is a derivation from gml:AbstractGMLType.  
The gml:description property element shall hold the definition if this can be captured in a simple text string, or the gml:descriptionReference property element may carry a link to a description elsewhere.
The gml:identifier element shall provide one identifier identifying this definition. The identifier shall be unique within the dictionaries using this definition. 
The gml:name elements shall provide zero or more terms and synonyms for which this is the definition.
The gml:remarks element shall be used to hold additional textual information that is not conceptually part of the definition but is useful in understanding the definition.

Element Information

Model

gml:metaDataProperty* , gml:description{0,1} , gml:descriptionReference{0,1} , gml:identifier , gml:name* , gml:remarks{0,1}
Children: gml:description, gml:descriptionReference, gml:identifier, gml:metaDataProperty, gml:name, gml:remarks

Attributes

QName Type Fixed Default Use Inheritable Annotation
gml:id ID required 
The attribute gml:id supports provision of a handle for the XML element representing a GML Object. Its use is mandatory for all GML objects. It is of XML type ID, so is constrained to be unique in the XML document within which it occurs.

Used By

Complex Type gml:DictionaryEntryType

Source 

<element name="Definition" type="gml:DefinitionType" substitutionGroup="gml:AbstractGML">
  <annotation>
    <documentation>The basic gml:Definition element specifies a definition, which can be included in or referenced by a dictionary. The content model for a generic definition is a derivation from gml:AbstractGMLType. The gml:description property element shall hold the definition if this can be captured in a simple text string, or the gml:descriptionReference property element may carry a link to a description elsewhere. The gml:identifier element shall provide one identifier identifying this definition. The identifier shall be unique within the dictionaries using this definition. The gml:name elements shall provide zero or more terms and synonyms for which this is the definition. The gml:remarks element shall be used to hold additional textual information that is not conceptually part of the definition but is useful in understanding the definition.</documentation>
  </annotation>
</element>

Sample