The definition for abate is "Become less in amount or intensity." Used in a sentence: Just when it seemed the rain would never stop, the storm suddenly began to abate.

The definition for compulsion is "An irresistible impulse." Used in a sentence: Tamar, a shoe fanatic, could not resist the compulsion to buy the shiny red boots.

The definition for periodic is "Occurring at regular intervals." Used in a sentence: The periodic innterruptions of the cuckoo clock prevented Li from concentrating.

The definition for placebo is "An inactive substance used in medical testing." Used in a sentence: Tom, who had taken the placebo, found that his allergy symptoms did not go away.

The definition for stifle is "To repress or discourage." Used in a sentence: Amy tried ineffectively to stifle her giggles after she read Susan's note in class.