Poles of the 17th century assumed that "szlachta" came from the German "schlachten" ("to slaughter" or "to butcher"); also suggestive is the German "Schlacht" ("battle"). Early Polish historians thought the term may have derived from the name of the legendary proto-Polish chief, Lech, mentioned in Polish and Czech writings.
What did the poles of the 17th century think the term szlachta came from?
German "schlachten"