Although the family name of Belcher is a prominent one in English and American history, it is actually Old French in origin. The ancestor of the Belcher family came to England from France, as part of William the Conqueror's army that came to England in the Norman Conquest of 1066 A.D.
(Microbiology) any of several viruses whose genetic specification is encoded in RNA rather than DNA and that are able to reverse the normal flow of genetic information from DNA to RNA by transcribing RNA into DNA: many retroviruses are known to cause cancer in animals.
Retroviruses belong to the Retroviridae family of viruses. Their genetic material consists of ribonucleic acid (RNA), instead of deoxyribonucleic acid (DNA). Viruses of this type also contain reverse transcriptase. Retroviruses are known to lead to certain types of cancers in both humans and animals, as well as a range of viral infections. Human Immunodeficiency Virus (HIV), the virus that causes Acquired Immune Deficiency Syndrome (AIDS), is one example.