Sub isdefinename()
Dim msg As String, n, zz
For Each n In Names
  Set zz = Nothing
  On Error Resume Next
  Set zz = n.RefersToRange
  On Error GoTo 0
  If Not zz Is Nothing Then
    If zz.Address(external:=True) = Selection.Address(external:=True) Then
      If msg = "" Then msg = n.Name Else msg = msg & vbLf & n.Name
    End If
  End If
Next n
If msg = "" Then msg = "Selection is not a Name"
MsgBox msg
End Sub