When it comes to adjectives related to age, choosing between eldest and oldest can cause some people to grow a few premature gray hairs. The words seem interchangeable and their preferred usage is unclear. Why say oldest person alive and not eldest person alive? What exactly is the difference between the two?
According to Merriam-Webster, the most significant distinction is that eldest and elder are only ever used to refer to people. An antique can’t be the eldest in a collection, only the oldest. But your older sister could be the eldest among your siblings.
Eldest is most often used in the context of people who are related either as family or as part of a group for comparison purposes. It also doesn’t necessarily have to refer to age. If someone joins a chess club in their 80s, they might be the oldest person in the group, but that doesn’t mean they’re necessarily the eldest. That would describe the member of the group who’s been there the longest, even if that person is in their 30s.
Oldest can certainly refer to people, but it’s best to opt for eldest when comparing people within a social or familial community. And remember that elder can also be used as a noun, while older cannot. You would respect the elders in your family, not the olders.
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A version of this article was originally published in 2020; it has been updated for 2023.