noun🔗Share西格玛，Σ。 The eighteenth letter of the Classical and Modern Greek alphabets, the twentieth letter of Old and Ancient."In Greek class, we learned that sigma is the eighteenth letter of the alphabet. "在希腊语课上，我们学到**西格玛（sigma）**是希腊字母表的第十八个字母。languagewritingsignChat with AIVocabulary GamePractice Reading
noun🔗Share求和符号, Σ (西格玛)。 The symbol Σ, used to indicate summation of a set or series."The math textbook explained how to use the sigma notation (Σ) to easily represent the sum of many numbers in a sequence. "这本数学课本讲解了如何使用求和符号 (Σ) ，也叫做西格玛符号，来简便地表示一个数列中许多数字的总和。mathnumbersignstatisticsChat with AIVocabulary GamePractice Reading
noun🔗Share西格玛，标准差。 The symbol σ, used to indicate one standard deviation from the mean, particularly in a normal distribution."The teacher explained that a score one sigma above the mean in the math test meant the student performed better than most of the class. "老师解释说，数学考试中，如果一个分数比平均分高出一个西格玛（标准差），就意味着这个学生的表现优于班里的大部分同学。mathstatisticsChat with AIVocabulary GamePractice Reading
