To obliterate something means to destroy it so completely that almost nothing remains. When a powerful storm obliterates a sandcastle on the beach, it doesn't just damage it or knock it over: it smashes it so thoroughly that you can barely tell a castle was ever there.

The word suggests total, devastating destruction. A single pencil mark can be erased, but when you obliterate writing, you might scribble over it so heavily that no one could possibly read what was underneath. In war, bombs might obliterate entire buildings, leaving only rubble and dust. A record-breaking performance can obliterate the previous record, crushing it so decisively that the old mark seems tiny by comparison.

You might hear someone say a soccer team obliterated its opponent with a score of 8-0, or that a new discovery obliterated an old scientific theory. While the word sometimes gets used as exaggeration (your little brother probably didn't literally obliterate his dinner, even if he ate it very quickly), true obliteration means wiping something out so completely that it's essentially gone.