An Etymological Dictionary of the German Language/Annotated/Knecht
Knecht, masculine, ‘servant,’ from Middle High German knëht, Old High German chnëht, masculine, ‘boy, youth, fellow, man, squire,’ often also ‘hero’; compare Anglo-Saxon cniht, masculine, ‘boy, youth, man capable of bearing arms, hero,’ English knight; probably a West Teutonic word, unknown to Gothic and Scandinavian (Danish knegt and Swedish knekt are borrowed). The same variety of meanings in West Teutonic words is found in Knabe and Knappe (compare also Anglo-Saxon mago, ‘son, boy, man, champion,’ see too Kerl). However probable its close connection with Knabe and Knappe may be, yet it is not possible to define it strictly. Kneckt is more probably allied to the root ken, from Aryan gen (Latin genus, γένος, Latin gi-gn-o, γίγνομας), than Knabe, because a suffix -ëht exists in Teutonic.