- to transfer something bad or harmful, especially pathogens or allergens, to (a person or thing): Wash the cutting board after using it for meat, or you may cross-contaminate your vegetables with bacteria from the meat.
- to allow the unwanted mixture of minute amounts of one substance into another, as with laboratory specimens: The lung secretions were left to sit too long before analysis, cross-contaminating the specimen with particles from the air.
- to mix ideas, information, etc., in such a way as to compromise their integrity or reliability: I don't want to cross-contaminate the data—I need the files generated for each day to stay separate.
