ˌanəfə̇ˈlaksə̇s noun
( plural anaphylax·es -kˌsēz)
Etymology: New Latin, from ana- + -phylaxis (as in prophylaxis )
1. : hypersensitivity (as to foreign proteins or drugs) that is marked by a tendency to intense systemic reaction and that results from specific sensitization following one or more usually parenteral contacts with a sensitizing agent and seen chiefly in experimental animals but manifested in man in acute serum sickness and in severe or fatal reactions to second or later administrations of certain drugs (as penicillin)
2. : anaphylactic shock