DBA_VIEWS

Description of all views in the database

Columns
   ___________________________
 
   OWNER
      Owner of the view
   VIEW_NAME
      Name of the view
   TEXT_LENGTH
      Length of the view text
   TEXT
      View text
   TYPE_TEXT_LENGTH
      Length of the type clause of the object view
   TYPE_TEXT
      Type clause of the object view
   OID_TEXT_LENGTH
      Length of the WITH OBJECT OID clause of the object view
   OID_TEXT
      WITH OBJECT OID clause of the object view
   VIEW_TYPE_OWNER
      Owner of the type of the view if the view is an object view
   VIEW_TYPE
      Type of the view if the view is an object view
   SUPERVIEW_NAME
      Name of the superif view is a subview

Examples (SQL*Plus):

View the definition of myview:

set LONG 1000
select TEXT from DBA_VIEWS
where owner='myowner' and view_name='myview';

1000 should be more than large enough to read most view definitions, but if you want to set this exactly look at the TEXT_LENGTH column:

select TEXT_LENGTH from DBA_VIEWS
where view_name = 'myview';

Related:
ALL_Views