These two words are among the most-often interchanged of our near-identical troublesome twins. Many of us have seen a sign in a big-box drugstore directing us to the “Stationary” section. Such mix-ups occur in lots of writing.

And of course our spellcheckers won’t help us, because even if we choose the wrong word, it’s still a word, and the dumb machines can’t tell the difference. So the best cure for the problem is prevention, and the best prevention is a good mnemonic device—a memory hook.

Stationary means “not moving, staying in one place.” And stationery refers to the paper we use for correspondence. The trouble spot is the choice of which vowel to use in the last syllable—an a or an e?

One of the most-common fixes is to visualize a letter, sealed in an envelope. Notice that there are two e’s in letter, which makes it easy to link it to stationery. Like almost all good mnemonics, this one is clear and simple—and it works. (Some people prefer Envelope, which is okay too.)

If you want a longer one, try: “The post office is stationary, but its contents are stationery.” Or even better, make up your own way to remember the difference. If you come up with a good one, let us know. Don’t bother with stationery, just shoot us an email.