What is the meaning of false positive and false negative results?

In pharmaceuticals false positive and false negative results are commonly used terms. What are false positive and false negative results? I would like explain this. 

False positive results: False positive results means actual result would be negative but because of the error (problem in testing method/sampling/handling) positive results found. This is called false positive result. For  example in case of Microbial limit testing (MLT), in actual no contamination was present in the sample but because of error in practise, the analyst contaminated the product during analysis and growth found in the product after incubation.

False negative results: False negative results means actual result would be positive but because of error negative results found. For example in case of Microbial limit testing (MLT) of product, contamination was present in the product but because of pouring very hot media in the product petriplates no growth found in product after incubation. 

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