ember

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A small, glowing piece of coal or wood, as in a dying fire.
• noun The smoldering coal or ash of a dying fire.

from The Century Dictionary.

• noun Literally, a circuit; a course; specifically, a regular (annual, quarterly, etc.) course; the regular return of a given season: a word now used only in certain compounds, namely, ember-days, -eve, -fast, -tide, -week, and in the derivative embering. See the etymology.
• noun A small live coal, brand of wood, or the like; in the plural, live cinders or ashes; the smouldering remains of a fire.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Making a circuit of the year of the seasons; recurring in each quarter of the year.
• adjective (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.
• noun A lighted coal, smoldering amid ashes; -- used chiefly in the plural, to signify mingled coals and ashes; the smoldering remains of a fire.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A glowing piece of coal or wood.
• noun Smoldering ash.
• adjective Making a circuit of the year or the seasons; recurring in each quarter of the year, as certain religious days set apart for fasting and prayer.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a hot fragment of wood or coal that is left from a fire and is glowing or smoldering