What is "ember days"

Ember \Em"ber\, a. [OE. ymber, AS. ymbren, ymbryne, prop., running around, circuit; ymbe around + ryne a running, fr. rinnan to run. See Amb-, and Run.] Making a circuit of the year of the seasons; recurring in each quarter of the year; as, ember fasts.

Ember days (R. C. & Eng. Ch.), days set apart for fasting and prayer in each of the four seasons of the year. The Council of Placentia [A. D. 1095] appointed for ember days the Wednesday, Friday, and Saturday after the first Sunday in Lent, Whitsuntide, the 14th of September, and the 13th of December. The weeks in which these days fall are called ember weeks.

In the liturgical calendar of the Western Christian churches, Ember days are four separate sets of three days within the same week — specifically, the Wednesday, Friday, and Saturday — roughly equidistant in the circuit of the year, that are set aside for fasting and prayer. These days set apart for special prayer and fasting were considered especially suitable for the ordination of clergy. The Ember Days are known in Latin as the quattuor anni tempora (the "four seasons of the year"), or formerly as the jejunia quattuor temporum ("fasts of the four seasons").

The four quarterly periods during which the ember days fall are called the embertides.