Death in the family
A death in the family is a bereavement where a member of one’s family dies. A death in the immediate family involves the death of one’s spouse, parent, sibling, or child.
A death in the family is an ironclad excuse from social engagements, and is normally considered a legitimate excuse for absence from work, even where companies do not have an official policy on the subject. A death in the immediate family used to be the only acceptable excuse for certain high-level social obligations, such as an invitation to the White House. Such rules have been relaxed since about the mid-twentieth century.
In the 21st Century, a death in the family is probably the only remaining bereavement where a person might observe mourning.