Someone who identifies with at least some Catholic teachings and traditions, likely because of upbringing, but is not active in the Catholic Church.
A "cultural Catholic" was raised in a Catholic family, probably attended Catholic services as a child, and possibly attended Catholic school for at least a few years. Catholic teachings and traditions may influence the person's behavior, decision-making, and holiday celebrations, but a "cultural Catholic" no longer attends Mass or practices his or her faith. The person may continue to attend weddings, funerals, and other events that take place in the Catholic Church but does so out of consideration for family and friends rather than as an expression of his or her own faith.
That family goes to the movies rather than to Mass on Christmas Day, but they still incorporate a manger into their holiday decor because they're "cultural Catholics."