The Hebrew word apher (אֲפֵר) means ashes — the residue left after something has been burned. It is closely related to the more common epher (H665). Ashes in the ancient Near East were a powerful symbol of mourning, penitence, humility, and mortality. To sit in ashes or put ashes on the head was a visible expression of grief and contrition.
Ashes carry profound theological symbolism in Scripture. They represent the ultimate humility of mortality — 'from dust you came, to dust you shall return.' When Job sat in ashes, he acknowledged his creaturely limitation before the Creator. When the prophets called for ash-wearing, they were calling God's people to genuine contrition. Yet Isaiah's great reversal — 'beauty instead of ashes' — announces the gospel: God transforms our grief and mortality into glory.