The term DEVIATION SYMBOL STANDARD can be broken down into two crossword solutions: SIGMA (5 letters) and DISPERSION (10 letters). SIGMA is a Greek letter that is used in mathematics to represent standard deviation, which is the measure of how spread out numbers are in a set. DISPERSION is the process of spreading out or distributing something over an area or throughout a population. In statistics, DISPERSION is used to measure the spread of data points around the mean. Together, these two terms refer to the standard deviation symbol, which is used to represent the measure of DISPERSION in a set of data.