The decade of the 1820s, 1920s, 2020s, etc.
The decade of one's life from age 20 through age 29.
The waiter was in his twenties.
(temperature, rates) The range between 20 and 29.
She shivered; twenties by the water felt different than twenties in the mountains.
A banknote with a denomination of 20.
The waiter’s face lit up when I gave him a twenty.
10-20 (location).
What’s your twenty, good buddy?
An old English division of infantry.