Green’s Dictionary of Slang

behind prep.

1. [1930s+] (orig. US) involved with, concerned about, believing in.

2. [1950s+] (US black) as a result of, as a consequence of, in reference to.

3. [1960s+] (orig. US) in full understanding of.

4. [1970s] (orig. US) excited by, obsessed with.

In phrases

get behind (v.) [the image of putting one’s weight behind]

1. [late 19C] (US) to start smoking or drinking.

2. [1900s; 1960s+] to make a commitment to an idea, a job, a person etc.

3. [1970s+] (also groove behind) to understand, to enjoy, to appreciate [groove v. (2)].

SE in slang uses

In phrases

behind a dime (adv.) [SAmE dime, the tiny ten-cent coin; i.e. there is no way such a person can ‘hide’]

[1980s+] (US) to any extent, under any circumstances; usu. in phr. I wouldn’t trust (someone) behind a dime.

behind one’s door (also behind the door)

[1950s+] (UK prison) locked up in solitary confinement; also as an order, behind your doors! get into your cell!

behind oneself (adj.) [SE behind, backward]

[late 19C] out of date, out of fashion, not up with the latest situation.

behind someone like a slave-driver (adj.) (also behind someone like a tak-tak) [the tak-tak or acoushi ant, a fierce pest]

[20C+] (W.I.) begging, harassing, pressurizing.

behind the parade (adj.)

[1920s+] (orig. US black) old-fashioned, passé.

behind the ramp [the ramp implies some form of desk]

[1980s] a phr. describing anyone in authority, esp. a police officer or prison warder.

behind the scale (n.) [drugs are bought in bulk then weighed out in smaller measures for sale; the image is of a small shopkeeper behind the counter]

[1980s+] (US black) a drug seller’s place of business, thus the weighing and selling of the drug.

behind the walls (adv.) (also inside the walls)

[20C+] (US Und.) in prison.

go behind something (v.)

[1940s] (US black) to argue with something, to contradict the facts.