1. adjective Of, leading to, or causing an outcome that will either be a total success or a total failure. Often hyphenated when used before a noun. The decision to merge the two companies will likely prove a make-it-or-break-it move for both. These next few months are going to be make it or break it for us financially.

2. verb To either totally succeed or fail completely; to cause or result in such an outcome. With so many tumultuous things going on in the world, it feels as though the human race is going to make it or break it in coming years. In this industry, having a public, social following of users (or a lack thereof) will always make it or break it for a company.