yellowback

plural yellowbacks · alternative yellow-back

1. obsoleterareAny member of species Sciades parkeri of sea catfish, having yellow coloration on the upper part of its body.First known use 18th–19th c.
2. A cheap novel with a yellow cover; any cheaply reproduced novel, typically with sensational content.First known use 19th c.

   She felt she would like a corner in the English room for the afternoon, a book and an occasional remark—Mr Barnes of New York—she would not be able to read her three yellow-backs in the German bedroom.

   1915, Dorothy Richardson, Pointed Roofs, Broadview, published 2014, page 173

3. UShistoricalA monetary note redeemable in gold; a gold certificate.First known use 19th c.