Keystone

/kˈiːstə‍ʊn/

/ˈkiˌstoʊn/

Keystone

a stone located at the top center of an arch, keeping all the other stones together

synonyms : headstone

the most significant part of an argument, belief, or plan on which everything else depends

synonyms : anchor

Examples

1. An essay needs a keystone, too.

2. Most places have keystone species.

3. The regulatory process under the Bush administration for base Keystone went very easily.

4. Cleveland's keystone, Daugherty, made his second straight appearance.