试图将变量传递给URL PHP

Here is my code:

<?php
    $categoryName = $_GET['categoryName'];

        $json_data= json_decode($json = file_get_contents("../json/pages.json"), TRUE);
        function callDefinition(){
            if($json_data[$termName]){
                foreach($json_data[termName] as $key => $val){
                    echo $val;  
                }
            }
        }
?>
    <html lang="en">
        <head>
              <meta charset="utf-8">
              <title>RBC Interactive Glossary</title>
              <link rel="stylesheet" href="../css/templateStyle.css">
        </head>

        <body>
            <div id="topHalf">
                <img src="../img/home.png" id="homeButton"/>

                <button id="categoryTitle"> <?php echo $categoryName; ?> </button>
                <?php foreach($json_data[$categoryName] as $term => $definition): ?>
                <button class ="defaultButtonLeft"> <?php echo $term ?></button>
                <?php endforeach; ?>
            </div>

            <div id="bottom">

            </div>

            <script src="../js/jquery-1.7.2.min.js"></script>
            <script src="../js/app.js"></script>
        </body>
    </html>

What happens here is I load some terms based on a category that the user clicks on in the last page the user was in, This was an HTML page that used javascript to pass a variable into the URL. Now I'm trying to do the same thing here (Passing a variable into the URL) but problem I'm running into is a bunch of "cant do that" sites. I don't know if it's just bad googling on my part or what. I was wondering if somebody could tell me how to detect what button was clicked, then pass that buttons specific $definition into the URL which will be transferred to another php page. Is this possible?

Here is my other page, basically a copy of the previous one with minor differences to load the term as a button title, then the deifnition:

<?php
    $termName = $_GET['termName'];

        $json_data= json_decode($json = file_get_contents("../json/pages.json"), TRUE);
        function callDefinition(){
            if($json_data[$termName]){
                foreach($json_data[termName] as $key => $val){
                    echo $val;  
                }
            }
        }
?>
    <html lang="en">
        <head>
              <meta charset="utf-8">
              <title>RBC Interactive Glossary</title>
              <link rel="stylesheet" href="../css/templateStyle.css">
        </head>

        <body>
            <div id="topHalf">
                <img src="../img/home.png" id="homeButton"/>

                <button id="termTitle"> <?php echo $termName; ?> </button>
                <?php foreach($json_data[$termName] as $term => $definition): ?>
                <button class ="defaultButtonLeft"> <?php echo $definition ?></button>
                <?php endforeach; ?>
            </div>

            <div id="bottom">

            </div>

            <script src="../js/jquery-1.7.2.min.js"></script>
            <script src="../js/app.js"></script>
        </body>
    </html>