The definition of a shut in is a person who does not leave his or her home.
An example of a shut in is an elderly lady who hasn't left her house for a month because she is afraid to see people.
- confined to one's home, an institution, etc. by illness or infirmity
- inclined to shun others; withdrawn
an invalid who is shut-in
A person confined indoors by illness or disability.
- Confined to a home or hospital, as by illness.
- Disposed to avoid social contact; excessively withdrawn or introverted.