Definitions for "Content Item"
A Content Item is a discrete piece of content within the Joomla hierarchy. A Content item can be an article, a content category, a menu item or a link. Usually Content Items are placed in the main body of your page. Content Item are the last in the Section/Category hierarchy or it can be a separate Static Content Item.
If this is referring to what I think it is, you might consider mentioning that Content Items can be in the form of a Content Item (inside the Section/Category hierarchy) or a Static Content Item.
a news or story you write and that is displayed in the main area of you site