Emily Dickinson Lexicon

FAST, n.¹

1. Abstinence from food; properly a total abstinence, but it is used also for an abstinence from particular kinds of food, for a certain time. Happy were our forefathers, who broke their feats with herbs. Taylor.
2. Voluntary abstinence from food, as a religious mortification or humiliation; either total or partial abstinence from customary food, with a view to mortify the appetites, or to express grief and affliction on account of some calamity, or to deprecate an expected evil.
3. The time of fasting, whether a day, week or longer time. An annual fast is kept in New England, usually one day in the spring. The fast was now already pest. Acts xxvii.