Dear Geist,
Why is the word scissors plural, and how did we fall into the habit of calling it “a pair of scissors” and then end up clumsily calling it “a scissors”? An egg beater, to name just one kitchen tool that has a lot more than two blades, is still one thing—just like scissors.
—Kindest Cut, Saskatoon SK
Dear Kindest,
Scissors is a plurale tantum—a word with the plural form for both singular and plural. The word hails from the Latin caesorium, a cutting instrument involving two blades. It entered Middle French as cisoire (singular) and cisoires (cisoires). Then in the 1400s it slid into English as a plural only. Who knows why? But we'll point out that scissors isn't the only plurale tantum. We've got glasses, pants, tweezers . . .
—The Editors