a technique in which a known DNA sequence is synthesized at high temperatures by means of a polymerase, producing millions of copies for statistical analysis: used in DNA fingerprinting, in detecting minute quantities of cancer cells, etc.
See polymerase chain reaction in American Heritage Dictionary 4
noun Abbr. PCR
A technique for amplifying DNA sequences in vitro by separating the DNA into two strands and incubating it with oligonucleotide primers and DNA polymerase. It can amplify a specific sequence of DNA by as many as one billion times and is important in biotechnology, forensics, medicine, and genetic research.