Definition of "penknife"

Every sin is damning without Christ. "The wages of sin is death". It is no great difference, if a man be killed, whether it be by a sword or a penknife. The least sin violates the whole law. He that offendeth in one point, is guilty of all.

1689, John Flavel, Christ Knocking at the Door‎

Presently the man took a reed pen from his satchel, and trimmed it with a little ivory knife, carved in the semblance of a fish."Oh, what a beauty!" cried Dan. "’Ware fingers! That blade is perilous sharp. I made it myself of the best Low Country crossbow steel. And so, too, this fish. When his back-fin travels to his tail — so — he swallows up the blade, even as the whale swallowed Gaffer Jonah."

1906, Rudyard Kipling, Puck of Pook's Hill

The logical distinction between genus and species can, of course, apply to any objects whatsoever. Thus, for example, the genus knife may be divided into several species, such as penknife, table knife, bread knife, razor, etc. We might define the penknife as a knife small enough to be carried in the pocket, with foldable, sheathable elements, characterized by the feature that one blade at least is always suitable for sharpening pencils and erasing ink spots. We are quite sure in which features all the members of a certain species agree, notwithstanding possible individual characteristics, say a monogram on one penknife, or a corkscrew in another.

1948, G. Rabel, Discovery‎