Lexical Vexations
Stationary adj. unmoving, staying in one place.
Stationery n. items used for letter writing, especially paper but also pens and the like.
Words in the Wild: If you don’t remain stationary while writing, your stationery will be sullied with deplorable penmanship.
I often see the word stationary used when the author intends to refer to stationery. Chicago offers the following mnemonic for remembering the difference: “try associating the er in stationery with the er in paper.”
Still vexed? You can find a complete list of the Word Blog’s lexical vexations here.