Aside from that, it will work with <dl> just as well, the CSS for hiding the block does not care what element its hiding!
// // You need to list all your submenus as an array in this manner
var hide_these = ['mymenu1','mymenu2','mymenu3','mymenu4','mymenu5'];
for ( i = 0; i<hide_these.length; i++ )
// ** UPDATED ** \\
document.getElementById(hide_these[i]).className = 'hide';
<dt><a href="#" class="submenu">Link One here</a></dt>