back in

present singular third person backs in · participle present backing in · participle past backed in · past backed in

1. To reverse a vehicle into a space.

   ... the engine driver drew over the points and at once backed into the siding. He backed in steadily and stopped. The siding would not hold the train, and the guard hooked off five waggons, and the engine ...

   1877, Great Britain, Parliament, House of Commons, Accounts and papers of the House of Commons, page 39

2. gamblingTo bet that a player or team will win, as opposed to bet that they will lose.

   1 more example

   1921, Henry Luttrell, Crockford’s: Or Life in the West, Sketch No. III Whatever you throw is your chance. I called five for the main, which is the out chance, and threw seven to it, which is the in chance. If I throw five first, I lose, and if seven I win. You can back me in by betting the odds, or you can back me out, by taking the odds, the bank answers either way.

1. In the past time of.

   back in the ’60s

   1 more example

   back in the time of the dinosaurs