1. substances that remain after a process such as evaporation, combustion, or filtration
2. traces of chemicals, especially pesticides, that remain on or in something

Examples

• The laboratory analyzed the residues left after the chemical reaction.
• Pesticide residues on fruits and vegetables can be harmful if not washed off.
• Oil residues from the spill contaminated the shoreline for months.
• The filter removed most contaminants but some residues remained.
• Scientists tested the soil for toxic residues from the old factory.
• Soap residues can build up in washing machines over time.
• The cleaning process left no visible residues on the surface.