Wilson score
Project-GC often use the term Wilson score as short for Lower bound of Wilson score confidence interval for a Bernoulli parameter, which is a statistical formula to calculate a statistical confidence. More information about the formula can be found at Wikipedia.
Wilson score is used in several places on the site, for example when determining the "best" geocaches based on both favorite points and number of logs. This is done on the page Top Favorite Caches (Lower bound of Wilson score).