Medical Definition of Human immunodeficiency virus. Human immunodeficiency virus: HIV, the cause of AIDS. HIV has also previously been called the human lymphotropic virus type III, the lymphadenopathy-associated virus and the lymphadenopathy virus. No matter what name is applied, it is a retrovirus. (A retrovirus has an RNA genome and a reverse transcriptase enzyme.
Definition of custody for English Language Learners. 1  law : the legal right to take care of a child (such as a child whose parents are divorced) : 2  the state of being kept in a prison or jail. : 3  the act of protecting or taking care of something.
Also called child custody. Law. the right of determining the residence, protection, care, and education of a minor child or children, especially in a divorce or separation. Compare joint custody, sole custody. 1. safekeeping, charge, watch. Custody, keeping, possession imply a guardianship or care for something. Custody denotes a strict keeping, as by a formally authorized and responsible guardian or keeper: in the custody of the sheriff.