How to spell USAD correctly?

If you meant to type "used", the correct spelling is with an "e". Alternatively, "USAD" may refer to the United States Academic Decathlon. If this is the case, make sure to capitalize all letters and provide the appropriate context in your writing.

• sad I felt sad when I heard the news of her passing.
• USAF
• USDA The USDA is responsible for regulating the safety and quality of the nation's food supply.
• used I used the bicycle to get to work today.

Putrefication

• nitrification
• petrifaction
• purification
• putrefaction
• putrification
• vitrification