Check this:
string xcontent = @"<?xml version='1.0' standalone='yes'?>
<EnDic11>
<EnDic>
<word>ant</word>
<meanings>
<meaning>test1</meaning>
<meaning>test2</meaning>
<meaning>test3</meaning>
</meanings>
</EnDic>
<EnDic>
<word>cat</word>
<meanings>
<meaning>test4</meaning>
</meanings>
</EnDic>
</EnDic11>";
XDocument xdoc = XDocument.Parse(xcontent);
var result = xdoc.Descendants("EnDic")
.Select(x=>string.Concat(x.Element("word").Value, "-", string.Join(",", x.Descendants("meaning").Select(y=>y.Value))))
.ToList();
result:
ant-test1,test2,test3
cat-test4