1. most covered with or marked by soot, dirt, or grime
Usage: superlative form of smutty
2. most indecent or obscene in content or language
Usage: informal; superlative form of smutty

Examples

• The chimney sweep’s clothes were the smuttiest after a long day of work.
• His hands were the smuttiest from working in the coal mine.
• The old factory windows were the smuttiest on the entire street.
• She refused to read the smuttiest magazines at the newsstand.
• The comedian’s smuttiest jokes were saved for the late-night show.