falsehood

"She made an intentional effort to be kinder to her brother after their argument. "

"The used car salesman was deceitful; he lied about the car's history to get a higher price. "

"The football team won the championship game, winning their rivals. "

"My sister is very helpful, especially when it comes to organizing things. "

"The politician's mendacious claims about his opponent were easily disproven. "

"Be sure to finish your homework before you go to bed!"

"My brother and I both attend the same high school. "

"Actually, I had nothing to do with that incident."

"Important types of property include real property (land), personal property (other physical possessions), and intellectual property (rights over artistic creations, inventions, etc.)."

"My teacher made a statement about the importance of studying hard. "

"The politician spoke at the school assembly about the importance of community involvement. "

"Her constant mendacity made it impossible to trust anything she said. "