Mourning sickness is a collective emotional condition of "recreational grieving" by individuals at the death of murder victims or celebrities.
It's a play on the term "morning sickness", a condition that affects more than half of all pregnant women.
Some critics have described the public displays of mourning as "phony" and more for the benefit of the people grieving than for the victims, families or individuals that they are grieving for. In Britain, The Guardian newspaper compared the widespread expression of grief by strangers to that seen after the death of Princess Diana. The paper cited the 2004 Civitas think-tank, which described such grief as "mourning sickness", related to people's own emotional needs, rather than any real rapport with the deceased.