Although one of the least common definitions, a "line" can also mean 1 fluid oz of codeine cough syrup. For example, some people who sell the stuff will sell it by the "line" for anywhere from like 30-100 dollars.

Noun: a friend who is usually only called upon by a friend when a more primary/prominent friend is unavailable.

Taken from the term “second string” in an athletic competition situation. In football, if the star quarterback gets injured during a play, the second string is called off the bench to replace him/her. A “Second String Friend” is essentially benched until needed, if ever.

Synonyms: Plan B, Second Choice, Secondary Friend, Benched Until Needed

Set someone up, plot against, conspire against one.

A 'line'(for lack of better word) of any powdered drug that is snorted, often through a rolled up 100 dollar bill.

Powdered substance (usually cocaine) that has been separated into multiple lines of powder usually by using a credit card or razor. These lines of powder are then sucked up through the nose usually using a rolled up dollar bill or an empty pen tube.

powdered cocaine, usually sniffed

Money, funds, Currency.

Like receiving a wire transfer aka "money transfer" . A wire is in essence a line. Sometimes we hear the saying "life line", this could mean emergency funds.