The Composite Cross is 'composite' in the sense that it is composed of multiple parts. These may be parts may include one or more additional cross-beams, a crown, a wreath, or anything else that gives some additional meaning for the cross.
A composite cross can also relate to crosses with multiple meanings. But since a cross can mean different things to different people, all crosses have multiple meanings.
For a list of crosses (and their images) composed of multiple elements, see Adorned Crosses.