any of various enzymes that promote polymerization, esp. of nucleic acids
See polymerase in American Heritage Dictionary 4
(pŏlˈə-mə-rāsˌ, -rāzˌ)
noun
Any of various enzymes, such as DNA polymerase, RNA polymerase, or reverse transcriptase, that catalyze the formation of polynucleotides of DNA or RNA using an existing strand of DNA or RNA as a template.