Lexical item

The verb and particle (in red) in each case constitute a particle verb construction, which is a single lexical item. The two words remain a catena even as shifting changes their order of appearance. The following trees illustrate polywords:

The component words of the polywords (in red) are continuous in the vertical dimension and are therefore catenae. They cannot, however, be construed as constituents since they do not form complete subtrees. The following trees illustrate idioms: