Option Explicit
Sub Test()
Dim rngWord As Word.Range
Dim vntaSilb As Variant
Dim vntSilb As Variant
vntaSilb = Array("ung", "heit", "keit", "nis")
For Each rngWord In ThisDocument.Words
For Each vntSilb In vntaSilb
If InStr(1, rngWord.Text, vntSilb, vbBinaryCompare) > 1 Then
rngWord.HighlightColorIndex = wdYellow
Exit For
End If
Next
Next
End Sub