Naomi said to call her Mara because “the Almighty has dealt very bitterly” with her. She described returning empty after going out full. Her explanation is in Ruth 1:20–21.
Naomi and Ruth arrive together in Ruth 1:19 at Bethlehem, and their return stirs the town, especially the women who recognize Naomi and question if it is really her. Naomi rejects her old name and asks to be called “Mara,” explaining that her life now feels marked by bitterness. These verses sit at the turning point of chapter 1: the travel from Moab ends and the Bethlehem storyline begins. Earlier, Naomi decides to return because conditions in Judah have improved, and Ruth binds herself to Naomi and to Naomi’s people and God (1:6–18).
Ruth 1:19–21 presents a public homecoming with a private interpretation. Naomi and Ruth arrive together in Bethlehem, and the town reacts strongly—especially the women who recognize Naomi and are startled by what has changed. Naomi then re-narrates her identity: she rejects “Naomi” and asks to be called “Mara,” tying her name to how life tastes to her now.
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Ruth 1:20-21, then read the surrounding section so the answer stays connected to the passage's flow.
20She said to them, "Don`t call me Naomi, call me Mara; for the Almighty has dealt very bitterly with me.
21I went out full, and Yahweh has brought me home again empty; why do you call me Naomi, seeing Yahweh has testified against me, and the Almighty has afflicted me?"