For example, the phrases "Wise fool", "Warm freezer", and "Legal murder" all have two words. In each one, the one word looks like the opposite of the other word.
You can have words that look opposite, but are right. For example, a "warm freezer" could be right. A freezer could be warm if it was turned off or left open.
The word oxymoron is an oxymoron; 'oxy' comes from the Greek word that means 'sharp', while 'moron' comes from the Greek word that means 'dull'.
Words that really are opposite to each other, would be words that just cannot be put together. For example, a "round square" could not happen because squares are not round.
Oxymorons sometimes appear in jokes. Sometimes, the joke is just to say that a pair of words are an oxymoron. For example, a joke that says that "glutted peasant" is an oxymoron. This means that peasants are usually hungry, if the word 'peasant' is opposite to 'glutted'
- "Oxymoron" at Rhetoric.byu.edu; retrieved 2012-1-14.