Longman Dictionary English From Longman Business DictionaryRelated topics: Statisticssix sigmasix sig‧ma /ˌsɪks ˈsɪgmə/ noun [uncountable] STATISTICS when the number of faults in a product or process is reduced to just over three per millionSix sigma means one is achieving process perfection 99. 9 percent of the time. ldoceonline.com
