late Old English aweg, earlier on weg "on from this (that) place;" see a- (1) + way (n.). Colloquial use for "without delay" (fire away, also right away) is from earlier sense of "onward in time" (16c.). Intensive use (as in away back) is American English, first attested 1818.
1. She ran away with a man called McTavish last year.
2. I have $100m hidden away where no one will ever find it.
3. He wiped away the blood with a paper napkin.
4. Her bed was crisply made, her clothes put away.
5. Ellery's return will help to chase away some of the gloom.