(American)

1. To leave, go suddenly. A shortening of ‘blow away’.

I better blow town before the cops come looking for me.

2. To perform fellatio (upon someone). In this sense the term may either derive from blow job or may be the source of that expression.

‘Who blew and were blown by those human seraphim, the sailors, caresses of Atlantic and Caribbean love.’ (Howl, poem by Allen Ginsberg, 1956)

3a. To smoke. In this sense the verb is typically used by devotees of cannabis.

Let’s get together and blow a couple of numbers.

3b. To sniff, snort. A cocaine (and occasionally amphetamine) users’ term for inhalation.

4. To be repellent. A rarer synonym of to suck, heard among school and college students.

‘Nice party, Dorothy’ ‘It blows.’ (Valentine, US film, 2001)

5. To play a musical instrument (not necessarily a wind instrument) in hip talk blow2 n

1a. Cannabis for smoking (hashish or marihuana). A drug users’ term.

1b. Tobacco. A usage encountered especially in the speech of prison inmates.

Both instances are based on the use of the verb to blow to mean smoke.

2. cocaine. The use of blow to mean cocaine spread from the USA to Britain in the later 1970s.

From the slang use of the verb to blow to mean both inhale and consume.

blow (someone) away vb

To kill someone, especially by shooting them. A widespread euphemism originally in American underworld and military usage.