beneficial
The definition for beneficial is "Helpful." Used in a sentence: there is no doubt that eating vegetables is beneficial to one's health.
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.
mundane
The definition for mundane is "Practical, ordinary." Used in a sentence: The flighty Caroline could not be troubled with mundane tasks such as paying her bills.
pretentious
The definition for pretentious is "Making unjustified claims." Used in a sentence: The pretentious boy said that he was the fastest runner, but he finished last in the race.
rehash
The definition for rehash is "To discuss again." Used in a sentence: "Sandra," said her mother, "I am tired of rehashing this same topic over and over."