OXYMORON

A figure of speech that combines contradictory terms .The most common forms of oxymoron involves an adjective -noun combination of two words. They can be devised in the meanings of sentences too.
Some examples...
Dark light
Open secret
Original copy
Bright shade
Pretty ugly
Anxious patient
Alone together
Act naturally
Serious joke
Deafening silence
Free rent
Clever fool
Dry lake 
Fresh sour cream 
Bitter sweet 
A little big
Just war 
....there are so many find more and add to your list!