A traffic delineator is either a traffic cone or one of those big round orange and reflective barrels that you see out on the highway especially during construction.
The traffic delineator can either be the post type or the barrel type that you see alongside the highway or in the middle of the highway or roads when you see them doing construction.
They sometimes use them to block off lanes and divert traffic to another lane while they are working on the road or highway.
The delineators used for marking the pavements right edge are usually white reflective in color while delineator Tube markers to separate traffic moving in opposite directions or to mark the left pavement edge are usually yellow in color for the reflective part.