What is the meaning of piggyback?

noun

• The act of carrying something piggyback.

verb

• Ride on someone's shoulders or back.
• Haul truck trailers loaded with commodities on railroad cars.
• Haul by railroad car.
• Support on the back and shoulders.
  • usage: "He piggybacked her child so she could see the show"
• Bring into alignment with.
  • usage: "an amendment to piggyback the current law"

adverb

• On a railroad flatcar.
  • usage: "the trailer rode piggyback across the country"
  • synonyms: pickaback, pig-a-back
• On the back or shoulder or astraddle on the hip.
  • usage: "she carried her child piggyback"
  • synonyms: pickaback, pig-a-back