combustion
The definition for combustion is "Act of burning." Used in a sentence: Campers must use fire with great caution to prevent combustion of the parched brush.
defiant
The definition for defiant is "Showing bold resistance." Used in a sentence: The defiant toddler refused to leave the park.
dubious
The definition for dubious is "Questionable." Used in a sentence: Karl found Kevin's claim that he was sick dubious, as he had just seen him playing football.
heed
The definition for heed is "To pay attention to." Used in a sentence: "Heed my advice," the fortuneteller warned Sebastian when he tried to ignore her prophecy.
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.