What is Contamination?
1 : the presence of particles, chemicals, and other undesirable substances, such as on or in a process tool, in a process liquid, or in a cleanroom environment. [SEMATECH]
Also see area contamination and particulate contamination.
2 : three-dimensional foreign material adhering to a package (plastic or ceramic) or leadframe, or parent material displaced from its normal location and similarly adhered. Adherence means that the particle cannot be removed by an air or nitrogen blast at 20 psi. [SEMATECH]
Also see stain.