Как по Английски будет девятый десяток

cardinal number

Equivalent to the product of eight and ten; ten less than ninety; 80.

Примеры использования:

Eighty miles north

plural noun

The numbers 80 through 89

Примеры использования:

The temperature is expected to be in the eighties (= between 80° and 89°) tomorrow., ronald reagan …

noun

A person's eighties are the period in which they are aged between 80 and 89

Примеры использования:

In your eighties my grandmother is in her eighties.