WordPress ships with jQuery (for longevity’s sake, as I write this WordPress is v3.2.1). To use jQuery in your plugins and themes “The Right Way” all you n

Solution for unrecognized $ sign when trying to use jQuery

jQuery(document).ready(function( $ ) {

// $ Works! You can test it with next line if you like
// console.log($);

});

Source: Using ‘$’ instead of ‘jQuery’ in WordPress | Digging Into WordPress