1. The transfer of active humoral immunity in the form of ready-made antibodies, from one individual to another. Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta, and can also be induced artificially, when high levels of human (or horse) antibodies specific for a pathogen or toxin are transferred to non-immune individuals. (wikipedia.org)
2. A type of immunity acquired by the transfer of antibody from one individual to another, such as from mother to offspring. (biology-online.org)
3. The translocation of active humoral immunity from one individual to another in the form of custom-made antibodies. (wiktionary.org)
4. The short-term immunity that results from the introduction of antibodies from another person or animal. (Google Dictionary)
5. An impermanent form of acquired immunity in which antibodies against a disease are acquired naturally (as through the placenta to an unborn child) or artificially (as by injection of antiserum)). (wordnetweb.princeton.edu)