Recommended by Celaena Cheshire
"WEATHER" and "WHETHER"
"Weather" refers to the atmospheric conditions. "Whether" is used to introduce alternatives or choices. Ex.: The weather is perfect for a picnic. I'm not sure whether to wear a jacket or not.
"STATIONARY" and "STATIONERY"
"Stationary" means not moving or not changing. "Stationery" refers to writing materials, such as paper, pens, and envelopes. Ex.: The car remained stationary at the traffic light. I need to buy some stationery for the office.