Stationary / Stationery
These are two different things, and I've seen so many "professionals" mix the two up that it drives me up the wall.
This is the act of standing still or lack of motion. I am standing in one place, therefore I am stationary.
This is your standard Letterhead, Business Cards, Envelope setup. Stationery refers to paper items that are written on.
Honestly, when I was 14 I didn't know the difference until somebody informed me of it. From then on I have known the difference. Unless you're 14, you don't have an excuse.
---> now <--- ex:
The car is stationary.
The paper is stationery.
"That being said, you could also get a paper weight stationery car and a stationary piece of paper.
Actually, it is most likely for you to get a piece of stationary stationery paper inside a stationary stationery box sitting in a stationary car."