cynical

(adjective)

 inclined to distrust or deny the goodness or sincerity of human motive

When you are cynical others doubt your motives.

decorum

(noun)

conformity to accepted standards of conduct; proper behavior

The usually belligerent agnostic acted with surprising decorum during the church service.

demagogue

(noun)

a leader who appeals to the emotions and prejudices of people, especially to advance his own power

Once the leader of the revolt defeated the dictator, he then became a demagogue.

demure

(adjective)

quiet and modest

Although she wanted to leave her abusive husband, she still tried to be demure while he was present.

deprecate

(verb)

to express disapproval of; to depreciate one's effort

Because the others deprecated his earlier ideas, he offered no new ones.

destitute

(adjective)

extremely poor; lacking necessities like food and shelter

Since they had no insurance, the fire which completely destroyed their home left them destitute.

diffifent

(adjective)

lacking in self-confidence; shy

After hearing of the man's accomplishments, it was especially hard to understand his diffident attitude.

dilemma

(noun)

a difficult choice; especially a choice between two equally undesirable alternatives

Whether I should repair my old car or purchase a new one was a real dilemma.

dilettante

(noun)

one who studies an art or science for mere amusement

Though just a dilettante, he practiced his piano with as much dilegence as a concert pianist.

disparity

(noun)

inequality; difference

He was forty and she was twenty, but their marriage was very happy despite the disparity in their ages.