Greenback is informal, suitable for casual speech rather than official documents.

Casual Term

Used primarily in American English, so it's less familiar to non-American English speakers.

American English

Can refer to any amount, not necessarily plural; 'greenback' can mean one dollar or many.

Not Plural Specific

Today, 'greenback' bonds are historical items, no longer issued or traded.

Historic Reference

In history, greenbacks were known as a safe investment due to government backing.

Safe Investment

They were created to fund the Union's efforts during the American Civil War.

Civil War Era

Refers to a specific species of trout with a greenish-hued back, found in the U.S.

Specific Trout

Most commonly used when talking about fishing, especially in regions home to the species.

Fishing Context

The greenback trout is considered a species of conservation concern.

Conservation Status

 bream and that's a really good meal you can see now it's going to kind of get it in its peak and it will eventually try and figure out how to actually sort of get it and might even hits it against the ground and try and sort of stun that fish before it then swallows it but that's gonna be a really good meal well done greenback heron and just in time as

See Elephants at Their...

 that the SDR could ever challenge the dollar's dominant role in international finance. And in fact, I think the only thing that the SDR would likely steal from the dollar under this scheme is its nickname, the "greenback."

A provocative way to...

 drive them to exhaustion males form dancing partnerships this young greenback male has teamed up with a more mature one to learn the routine