butter knife

a small knife with a dull blade, for cutting, serving, or spreading butter.

Origin of butter knife

First recorded in 1840–50

Set the butter on two plates, one on either side, with a butter-knife by each.

A Treatise on Domestic Economy |Catherine Esther Beecher
My mother went to housekeeping with six teaspoons and a butter-knife, and thought herself rich.

Fernley House |Laura E. Richards
Use the butter-knife, salt-spoon, and sugar-tongs as scrupulously when alone, as if a room full of people were watching you.

The Ladies' Book of Etiquette, and Manual of Politeness |Florence Hartley
Always make use of the butter-knife, sugar-spoon and salt-spoon, instead of using your knife, spoon or fingers.

Our Deportment |John H. Young

Always take butter with the butter-knife, and then do not forget to return that knife to the butter-plate.

The Scrap Book, Volume 1, No. 6 |Various