Mushuku means people in the Edo period whose names were excluded from Shumon-Ninbetsu-Aratame-Cho (The Village People Register of Religious Faith and Relationship) which is the equivalent of today's family register.
無宿（むしゅく）は、江戸時代において、現在の戸籍台帳と呼べる宗門人別改帳から名前を外された者のことである。