oxymoron
rhetorical device that uses an ostensible self-contradiction to illustrate a rhetorical point or to reveal a paradox
en-GB/ˌɒksɪˈmɔːɹɒn/
en-US/ˌɑkˈsiˈmɔɹɑn/
rhetorical device that uses an ostensible self-contradiction to illustrate a rhetorical point or to reveal a paradox