quoting constants in php: "this is a MY_CONSTANT"

I want to use a constant in PHP, but I also want to put it inside double quotes like a variable. Is this at all possible?

define("TESTER", "World!");
echo "Hello, TESTER";

obviously outputs "Hello, TESTER", but what I really want is something like:

$tester = "World!";
echo "Hello, $tester";

outputs "Hello, World!".