(Contamination) is the introduction or occurrence of a contaminant in food or food environment.

Source: EUROSTAT

'contaminated site' means a site where there is a confirmed presence, caused by man, of hazardous substances of such a level that they pose a significant risk to human health or the environment taking into account current and approved future use of the land;

Source: EURO-Lex

Introduction into or onto water, air, soil or other media of microorganisms, chemicals, toxic substances, wastes, wastewater or other pollutants in a concentration that makes the medium unfit for its next intended use. 

Source: EEA Glossary