mid-15c., "forgetful, disposed to forget, heedless," from Latin obliviosus "forgetful, that easily forgets; producing forgetfulness," from oblivio "forgetfulness, a being forgotten"(see oblivion). Meaning "unaware, unconscious (of something)" is by 1862; it formerly was regarded as erroneous, but this is now the main meaning and the word has lost its original sense of "no longer aware or mindful." Properly it should be used with to, not of. Related: Obliviously; obliviousness.
