Green’s Dictionary of Slang

blow (someone) away v.

[ext. of SE use + southern dial. use or jazz use, for two bands to engage in an on-stage competition; the winner was deemed to have blown away its rival]

1. [1910s+] (orig. US black, also blow) to shoot dead.

2. [1960s+] to defeat decisively.

3. [1960s+] to make intoxicated with a drug or drink.

4. [1970s+] (orig. US teen) to impress, to bowl over, to astound.

5. [1980s] (US black) to defeat verbally.

6. [1980s+] to kill.