Double doubles, often used as adjectives.

A pair of nouns

For example, playing cards:

In bridge, the score is "double" when bidding, double.

Play a pair, such as two kings.

There is another pair, (right), such as two aces.

At this time, it is said that there are two pairs (twins).

Double precision floating point number In double programming, the word "double" is actually "double" precision.