The definition for diffident is "Lacking self–confidence." Used in a sentence: The diffident student never raised her hand in class, even when she knew the answer.

The definition for ecstatic is "Overwhelmingly emotional." Used in a sentence: They were ecstatic when their team won the championship game in the last second.

The definition for hedonism is "Belief that pleasure is the sole aim of life." Used in a sentence: The hedonism of the emperoro, who spent all his time giving parties, caused his downfall.

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.

The definition for pallid is "Lacking color." Used in a sentence: The nurse was worried by the patient's pallid face and shallow breathing.