An Etymological Dictionary of the German Language/schmatzen

by Friedrich Kluge

schmatzen, vb., ‘to smack the lips in eating,’ from the equiv. MidHG. smatzen, which also means ‘to kiss with a smack.’ The MidHG. word comes from an older equiv. variant smackezen, a derivative of MidHG. smacken, ‘to taste, savour.’