noun
millstone
MILL-stohn/ˈmɪlstəʊn/
A heavy burden or problem that slows someone down.
The traveler's burden has become a millstone, slowing every step.

Etymology
A heavy grinding stone became a figurative weight that slows someone down.
More examples
- The failing project becomes a millstone.
- Old obligations remain a millstone around her neck.
Forms
millstone
Similar words
- burden
- A broader responsibility or weight.
- encumbrance
- Something that restricts movement or progress.