You could list the words and their abbreviations in a two column table and run the following macro to replace words from the first column with those corresponding from the second.
http://www.gmayor.com/installing_macro.htm
Sub ReplaceFromTableList()
Dim oChanges As Document, oDoc As Document
Dim oTable As Table
Dim oRng As Range
Dim rFindText As Range, rReplacement As Range
Dim i As Long
Dim sFname As String
Dim sAsk As String
sFname = "C:\Path\Abbreviations.doc x" 'The table document
Set oDoc = ActiveDocument
Set oChanges = Documents.Open(Filename:=sFname, Visible:=False)
Set oTable = oChanges.Tables(1)
For i = 1 To oTable.Rows.Count
Set oRng = oDoc.Range
Set rFindText = oTable.Cell(i, 1).Range
rFindText.End = rFindText.End - 1
Set rReplacement = oTable.Cell(i, 2).Range
rReplacement.End = rReplacement.End - 1
With oRng.Find
.ClearFormatting
.Replacement.ClearFormatting
Do While .Execute(FindText:=rFindText, _
MatchWholeWord:=True, _
MatchWildcards:=False, _
Forward:=True, _
Wrap:=wdFindStop) = True
oRng.Select
sAsk = MsgBox("Replace - " & vbCr & oRng & vbCr + vbCr & _
"with - " & vbCr & rReplacement, vbYesNo, _
"Replace from Table")
If sAsk = vbYes Then
'oRng.FormattedText = rReplacement.FormattedText
oRng.Text = rReplacement.Text
End If
oRng.Collapse wdCollapseEnd
Loop
End With
Next i
oChanges.Close wdDoNotSaveChanges
lbl_Exit:
Exit Sub
End Sub