archaic
The definition for archaic is "Characteristic of an earlier time." Used in a sentence: In the world of high fashion, two–year–old shoes are considered positively archaic.
beneficial
The definition for beneficial is "Helpful." Used in a sentence: there is no doubt that eating vegetables is beneficial to one's health.
demeanor
The definition for demeanor is "Behavior towards others." Used in a sentence: Carlos was well liked because of his charming demeanor.
gargantuan
The definition for gargantuan is "Gigantic." Used in a sentence: The gargantuan monster towered over the ten–story bulding.
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.