PIGGYBACK

I. adverb also pickaback Etymology: alteration of earlier a pick pack, of unknown origin Date: 1565 up on the back and shoulders, on or as if on the back of another, II. noun also pickaback Date: circa 1590 the act of carrying ~, the movement of loaded truck trailers on railroad flatcars, III. adjective also pickaback Date: 1823 marked by being up on the shoulders and back , carried or transported ~: as, of or relating to the hauling of truck trailers on railroad flatcars, being or relating to something carried into space as an extra load by a vehicle (as a spacecraft), IV. verb also pickaback Date: 1952 transitive verb to carry up on the shoulders and back, to haul (as a truck trailer) by railroad car, to set up or cause to function in conjunction with something larger, more important, or already in existence or operation, intransitive verb to function or be carried on or as if on the back of another