A rigorous form of fasting which, in its most classic form, was limited to one meal per day, not taken before evening, and excluding all flesh meat, eggs, butter, cheese, and milk. Variations have been in force in various times and places.
[Note: This has been changed from Fr. Hardon's original definition, which appears to have been incorrect: “Abstinence from all flesh meat, with only eggs, butter, cheese, or milk allowed at the evening meal. Formerly a diet limited to bread, salt, vegetables, and water constituted a black fast during Lent.” See the Catholic Encyclopedia.]