Hi

The following code should do what you want, it exepects each word on it's
own line and expects the list to be in a sorted order. When a duplicate
word is found it deletes the entire line containing the duplicate word. The
comparisons case insensitive:

Public Sub RemoveDuplicateWords()
   Dim rngReplace As Word.Range
   Dim rngFound As Word.Range
   Dim strLastWord As String
   Dim strThisWord As String

   Set rngReplace = ActiveDocument.Content
   With rngReplace.Find
       .ClearFormatting
       .Replacement.ClearFormatting
       .Text = "<*>"
       .Replacement.Text = ""
       .Forward = True
       .Wrap = wdFindStop
       .Format = False
       .MatchCase = False
       .MatchWholeWord = False
       .MatchAllWordForms = False
       .MatchSoundsLike = False
       .MatchWildcards = True

       ' Find all occurrences in the document
       Do While .Execute

           '
           Set rngFound = rngReplace.Duplicate
           strThisWord = rngFound.Text
           
           ' Ignore the very first word found
           If LenB(strLastWord) > 0 Then
           
               ' If current word is the sane as the last then delete it
               If StrComp(strThisWord, strLastWord, _
                 vbTextCompare) = 0 Then

                   ' Each word on its own line so delete entire line
                   rngFound.Select
                   Selection.Expand wdLine
                   Selection.Delete
               End If
           End If
           strLastWord = strThisWord

           ' Setup range to continue the search after
           ' the text that we just found/deleted
           rngReplace.Collapse wdCollapseEnd
       Loop
   End With
End Sub

HTH + Cheers - Peter

Another approach to this kind of problem is to copy the list to Excel, use
its functions (like unique filter) then paste the last back to Word. For
one-off tasks, it's usually quicker than writing VBA code.