prophage
noun
pro·phage ˈprō-ˌfāj 
-ˌfäzh
: an intracellular form of a bacteriophage in which it is harmless to the host, is usually integrated into the hereditary material of the host, and reproduces when the host does
Example Sentences
Recent Examples on the Web Once activated, the prophage cuts itself out of the bacterial genome, replicates and then packages its DNA into phages. 
Quanta Magazine, 16 Oct. 2018 Known as a prophage, this stretch of foreign DNA can persist for generations before activating. Quanta Magazine, 16 Oct. 2018 In the right conditions—say, if the bacteria are damaged, stressed, or exposed to certain conditions—prophages can awaken. Beth Mole, Ars Technica, 1 Feb. 2018
Quanta Magazine, 16 Oct. 2018 Known as a prophage, this stretch of foreign DNA can persist for generations before activating. Quanta Magazine, 16 Oct. 2018 In the right conditions—say, if the bacteria are damaged, stressed, or exposed to certain conditions—prophages can awaken. Beth Mole, Ars Technica, 1 Feb. 2018 Word History
Etymology
pro- entry 1 + phage after French probactériophage, from pro- pro- entry 1 + bactériophage bacteriophage
Note: The French word probactériophage was introduced by André Lwoff and Antoinette Gutmann in "Recherches sur un Bacillus megatherium lysogène," Annales de l'Institut Pasteur, vol. 78, no. 6 (June, 1950), p. 734.
First Known Use
1951, in the meaning defined above
Medical Definition
prophage
noun
pro·phage ˈprō-ˌfāj -ˌfäzh
-ˌfäzh : an intracellular form of a bacteriophage in which it is harmless to the host, is usually integrated into the hereditary material of the host, and reproduces when the host does