delta

delta
/ˈdeltə; `dɛltə/ n
1 the fourth letter of the Greek alphabet (}, ) 希腊字母表的第四个字母（}, ）.
2 triangular area of alluvial land at a river's mouth, enclosed or crossed by branches of the river （河口的）三角洲
    the Nile Delta 尼罗河三角洲.

牛津英汉双解词典