Replacement for application launch icon?

I want to replace this icon I have which shows all the applications I have installed and can launch them by clicking it. What do I search? Is this called an app drawer? App launcher? What terminology is it and where can I find it? I am a little lost on this one.

Let people know what DE your on what panel / dock. Have you changed icon sets to see if it changes? That icon looks like a standard place holder icon may not have an icon associated with it.

Im using KDE Plasma with Plank dock. That icon in the image is provided optionally by plank.