The ashes of a red heifer burned entire (Numbers 19:5) when sprinkled on the unclean made them ceremonially clean (Hebrews 9:13).

To cover the head with ashes was a token of self-abhorrence and humiliation (2 Samuel 13:19; Esther 4:3; Jeremiah 6:26, etc.).

To feed on ashes (Isaiah 44:20), means to seek that which will prove to be vain and unsatisfactory, and hence it denotes the unsatisfactory nature of idol-worship. (Comp. Hosea 12:1).

Noah Webster's New International Dictionary of the English Language

1. (n. pl.) The earthy or mineral particles of combustible substances remaining after combustion, as of wood or coal.

2. (n. pl.) Specifically: The remains of the human body when burnt, or when returned to dust by natural decay.

3. (n. pl.) The color of ashes; deathlike paleness.