deviate
The teacher deviated from her custom and gave out no homework.
diffuse
The clowns in the play are mainly to diffuse a feeling of happiness.
discontent
To Galbraith, materialism had gone mad and would breed discontent.
diversion
Strangers and travelers were welcome sources of diversion, and brought news of the outside world.
doubtless
Doubtless he'll be bringing his guitar, as usual.
drawback
This is a good car; its only drawback is that it uses a lot of petrol.
duplicate
If you lose your key, I can give you a duplicate.