Vassal
As the system developed in the seventh century, the vassals were gangs of freemen who subjected themselves, in some degree of formality, to the authority of a leader, from whom they could expect to be fed, clothed and armed. The quality of a vassal was only in his fighting ability and the strength of his loyalty. The etymology (where the word came from) of "vassal" is from a Celtic word gwas "boy" that meant a young male slave, with a Latinised form, vassus that appeared in Salic Law (Rouche 1987 p 429), like the way  "knight" came from the from  Old English word cniht and similar words in Frisian and Dutch, all meaning "lad" .