1. (in genetic engineering) Any process by which eukaryotic cells take up foreign DNA in a form that is replicated and passed to daughter cells, thereby changing the genetic constitution of the cell line or organism concerned. It is synonymous with transformation in bacteria. Various techniques have been devised, depending on the nature of the recipient cell. The most popular are the use of liposomes, electroporation, microinjection, and biolistics. See genetically modified organisms (Feature).

2. (in microbiology) The uptake by a bacterium of DNA from a bacterial virus (bacteriophage). Compare transformation.