polymerase chain reaction

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun 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 as many as one billion times and is important in biotechnology, forensics, medicine, and genetic research.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun biochemistry a technique in molecular biology for creating multiple copies of DNA from a sample; used in genetic fingerprinting etc