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.
equitable
The definition for equitable is "Fair and equal." Used in a sentence: The judge made an equitable decision dividing the estate evenly among the sisters.
incumbent
The definition for incumbent is "Necessary as a duty or responsibility." Used in a sentence: It was incumbent on Jack to attend his father's retirement party.
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.
serenity
The definition for serenity is "Calmness." Used in a sentence: The serenity of the glassy sea soothed the sailors after the big storm.