squatter; unauthorized occupant
Legal or formal term for someone occupying a building or land without permission or legal title. Rare in everyday conversation; more common in news or legal contexts. Compare 不法占拠者.
See also: 不法占拠者
Several squatters had taken up residence in the abandoned house.
不法占拠者 is a more common and direct term for 'squatter' or 'illegal occupant'. 無断居住者 is rarer and slightly more formal, emphasizing the lack of permission rather than illegality.
Compound of 無断 (without permission) + 居住者 (resident, occupant).