What is the literary device where two words that are antonyms are placed together?

Question

e.g. soppy-stern, happy-sad, high-low, talkative-tacit.

First correct answer gets a cookie*

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Answer 1

That's an oxymoron. :D

Answer 2

Oxymoron. :D Like "Fast turtle."

Cookie? *Wobble chin*

Answer 3

do you mean an oxymoron were the statement is self contradictory such as parting is such sweat sorrow?

Answer 4

Don't forget "military intelligence"

Oxymoron is correct (though to me you don't look like an ox or a moron)