When referring to a test result and its statistical Significance, and when it’s deemed unlikely to have occurred by statistical error alone.
Based on a Bayesian model, the uplift probability isn’t a significance in the wikipedia sense, but we call it that anyway. Uplift probability is strictly the probability that the impact of a test is positive under the prior.
We accept that significance is 95% (the industry standard). This means that for a test to be a winner, we have to determine that the uplift is more than 0 with probability at least 95%.