fact of life—a thing, especially unpleasant, the existence of which cannot be ignored:
- The fact of someone’s presence on welfare rolls has sometimes been used against them. Cruel as that may seem it is a fact of life.
facts of life—(euph.) details of the human sexual functions, especially as told to children:
- Telling a child of the facts of life was one of the tasks that the family had abdicated to the schools.