The first part is related to Ugaritic 𐎓𐎌𐎚𐎊 (ʿšty, “one”), Akkadian 𒁹 (DIŠ /ištēn/, “one”). Compare Ugaritic 𐎓𐎌𐎚 𐎓𐎌𐎗 (ʿšt ʿšr, “eleven”).
עַשְׁתֵּי עָשָׂר • (ʕashtē ʕasár) m (feminine עַשְׁתֵּי עֶשְׂרֵה)