negate
The definition for negate is "To make invalid." Used in a sentence: Paula negated Tiffany's argument by proving that her main premise was false.
penurious
The definition for penurious is "Extrememly stingy." Used in a sentence: Ebenezer Scrooge was most penurious, refusing to give even a penny to charity.
precept
The definition for precept is "A general rule of action." Used in a sentence: All the students know Mrs. Brown's strict precept; no talking in class.
repel
The definition for repel is "To resist, reject." Used in a sentence: The soldiers made a massive charge to repel the invaders.
salvage
The definition for salvage is "To save from ruin." Used in a sentence: After the fire, Mrs. Han tried to salvage her family photos from the wreckage.