Filthy means extremely dirty or disgusting. A filthy kitchen might have food crusted on the counters, sticky spills on the floor, and dishes piled high with mold growing on them. Filthy clothes are so grimy and stained that they need thorough washing to get clean.

The word goes beyond ordinary dirt or mess. A little mud on your shoes makes them dirty, but shoes caked with weeks of mud, grime, and who-knows-what-else are filthy. A bathroom that hasn't been cleaned in months becomes filthy. When something is filthy, it's so unclean that it makes you not want to touch it.

People also use filthy to describe language that's crude or inappropriate. Filthy language means swearing or talking in vulgar ways. If someone has a filthy mouth, they use lots of crude words that polite people avoid.

Sometimes people use filthy in an exaggerated way that's almost playful: “My room is absolutely filthy!” when it just needs a good cleaning. But the word carries real weight when something is genuinely revolting or unacceptably dirty. Nobody wants to eat in a filthy restaurant or swim in filthy water, because filthy means dirty enough to be unhealthy or truly repulsive.