OXYMORON

Oxymoron is putting two contradictory words together

An Oxymoron is a combination of contradictory or incongruous words, such as 'Cruel Kindness' or 'Jumbo Shrimp' (Jumbo means 'large' while Shrimp means 'small'). It is a literary figure of speech in which opposite or contradictory words, terms, phrases or ideas are combined to create a rhetorical effect by paradoxical means.

Examples:
hot ice, cold fire, wise fool, sad joy, eloquent silence

Oxymoron.info

Oxymorons:
        39.   Act naturally
        38.   Found missing
        37.   Resident alien
        36.   Advanced BASIC
        35.   Genuine imitation
        34.   Good grief
        32.   Same difference
        31.   Almost exactly
        30.   Government organization
        29.   Sanitary landfill
        28.   Alone together
        27.   Silent scream
        26.   Living dead
        25.   Small crowd
        24.   Soft rock
        23.   New classic
        22.   Sweet sorrow
        21.   Childproof
        20.   Now and then
        19.   Synthetic natural gas
        18.   Passive aggression
        17.   Taped live
        16.   Clearly misunderstood
        15.   Peace force
        14.   Extinct Life
        13.   Computer jock
        12.   Plastic glasses
        11.   Terribly pleased
        10.   Tight slacks
        9.     Definite maybe
        8.     Pretty ugly
        7.     Twelve-ounce pound cake
        6.     Diet ice cream
        5.     Rap music
        4.     Working vacation
        3.     Jumbo Shrimp
        2.     Exact estimate
        1.     Microsoft Works