The reason that this arrangement is called a "repurchase" (repo) agreement is that it can often be executed in another form, also known as a "buy-sell." In this equivalent form of the transaction, party A "sells" the bond to B, and B simultaneously agrees to "sell it back" to A (that is, A agrees to repurchase it) at a future date. The difference between the future price and the initial price represents the "repo" interest charged by B for in effect lending the money to A.

Donald MacKenzie, An Engine, Not a Camera, loc. 1291