squalor
Extreme filth and poverty where living conditions are terrible.
Squalor means extreme dirtiness and poverty, a state where everything around you is filthy, neglected, and falling apart. When someone lives in squalor, their home might have garbage piled up, broken furniture, dirty dishes everywhere, and an overwhelming smell of decay.
The word describes conditions so severe that basic cleanliness and order have broken down completely. A bedroom with clothes on the floor is messy. A family struggling with money might have worn furniture and patched clothing but still keep their home clean and cared for. Squalor means the deterioration has gone far beyond either of these situations.
You might read about historical figures who discovered children living in squalor, which spurred them to create orphanages or reform laws. Charles Dickens wrote about the squalor of London's poorest neighborhoods in the 1800s, describing conditions so terrible they shocked readers into demanding change. Today, news reports might describe squalid conditions in abandoned buildings or refugee camps.
When you encounter squalor in books or history, it usually signals that something has gone seriously wrong and that people deserve better living conditions than they currently have.