Long before I was the wedding planner turned stationery designer, I always used the word stationary when referring to invitations, letterhead, and the likes. Of course as time passed, and the industry began providing tools such as the below image (Sapling Press), to help us in understanding that even though the words stationery and stationary sound very close (phonetically), there is a slight difference. Oh and their meanings are completely different too.
I am sure that I can safely speak on behalf of my fellow stationery designers that it is bothersome that the word "stationary" still continues to be used incorrectly.
Heidi Bartlett of idieh Design summed it up BEST when she designed this really great card to create awareness on how to use the word stationery when referring to invitations, and other paper related items.
So there you have it!
Doing my part to spread more awareness,