Sub Pluriel()
'Declare the variables used
Dim oRng As Range
Dim lngCase As Long
    'set a range to the word the cursor is in
    Set oRng = Selection.Words(1)
    'establish the case of the word
    lngCase = oRng.Case
    'if the word ends in a space or non-breaking space remove that space from the range
    oRng.MoveEndWhile Chr(32) & Chr(160), wdBackward
    'Collapse the range to its end
    oRng.Collapse 0
    
    If lngCase = 1 Then 'its upper case
        oRng.Text = "S" ' write S to the range
    Else 'its not upper case
        oRng.Text = "s" 'write s to the range
    End If
lbl_Exit: 'set a marker - not essential
    Set oRng = Nothing 'clear the range
    Exit Sub 'and finish
End Sub