The phrase "discrete units" refers to separate and distinct parts or components. It means that something is divided or categorized into individual and independent units, which may not be connected or related to each other. Full definition
Another reason we see that organisms are discrete in terms of their change is that they form discrete units that we call species. (religion.blogs.cnn.com)
By «panels,» I mean that the story was broken into discrete units, and each one was fairly self - contained, so you knew when to stop scrolling and read. (goodereader.com)