Abarim Publications' online Biblical Hebrew Dictionary
אפר
Linguists distinguish between two separate roots אפר ('pr), but at close inspection, these two may have been experienced as quite related by a Hebrew audience.
אפר I
The Hebrew root אפר ('pr I) is possibly comparable to verbs in other languages that mean to leap or be agile. Its sole extant derivative is the masculine noun אפר ('eper), meaning ashes (BDB Theological Dictionary wonders: "as light, flying?"). This decidedly negative word indicates worthlessness (Isaiah 44:20), disgust (Job 30:19), misery (Psalm 102:9), shame (2 Samuel 13:19) or humiliation (Genesis 18:27). Ashes in the Bible also serve as a symbol of mourning (Isaiah 61:3, Job 2:8).
אפר II
The second root אפר ('pr II) occurs in cognate languages in the meaning of to enclose or envelop. It's not used in the Bible. Its derivations:
- The masculine noun אפר ('aper), meaning covering or bandage (1 Kings 20:38 only).
- The masculine noun אפריון ('appiryon), of unclear meaning. It occurs only once as well, in the Song of Solomon 3:9, where Solomon makes some kind of chair. The kind is described by our word, and it's possibly some kind of recliner, a bed-like lounger.
In ancient Israel, people would indicate their state of mourning by wrapping themselves in sackcloth and covering themselves with ashes. Our two roots are obviously related.