even(夕方)から、誤ってnを落としたもので、語源的にはevensong(夕方)と同じ。
Like most of the explanations of names in Genesis, this is probably based on folk etymology or an imaginative playing with sound. ... In the Hebrew here, the phonetic similarity is between hawah, "Eve," and the verbal root hayah, "to live." It has been proposed that Eve's name conceals very different origins, for it sounds suspiciously like the Aramaic word for "serpent." [Robert Alter, "The Five Books of Moses," 2004, commentary on Gen. iii:20]