Noun

• S: (n) piggyback (the act of carrying something piggyback)

Verb

• S: (v) piggyback (ride on someone's shoulders or back)
• S: (v) piggyback (haul truck trailers loaded with commodities on railroad cars)
• S: (v) piggyback (haul by railroad car)
• S: (v) piggyback (support on the back and shoulders) "He piggybacked her child so she could see the show"
• S: (v) piggyback (bring into alignment with) "an amendment to piggyback the current law"

Adverb

• S: (adv) piggyback, pickaback, pig-a-back (on a railroad flatcar) "the trailer rode piggyback across the country"
• S: (adv) piggyback, pickaback, pig-a-back (on the back or shoulder or astraddle on the hip) "she carried her child piggyback"