buy in

/B AY1 IH0 N/
verb
  1. 1

    To accept an idea as valid; to join in on a concept.

  2. 2

    To invest as part of a group; to put one's personal stake in an investment.

  3. 3

    To buy back for the owner at an auction.

noun
  1. 1

    Support; agreement; blessing (in a secular sense).

    โ€œLet's show the idea around and get buy-in from marketing.โ€

  2. 2

    A tournament where a player must purchase all of his or her chips before the tournament starts.

  3. 3

    The amount that a player buys in for

Source: https://en.wiktionary.org/wiki/buy%20in, https://en.wiktionary.org/wiki/buy-in