Stationary or stationery?

Stationary means not moving; stationery is paper and envelopes.

stationary
The car was stationary at the lights.
stationery
She ordered new stationery with her address on it.

To rememberStationery has an e, like envelope.

NotI need some new stationary.

SayI need some new stationery.

WhyPaper and envelopes: stationery, e for envelope.