phoresy (n.) Look up phoresy at Dictionary.com
"association between organisms in which one is carried on the body of another but is not a parasite," 1914, from French phorésie (1896), from Greek phoresis "being carried," from pherein "to carry," from PIE root *bher- (1) "to carry; to bear children" (source also of Sanskrit bharati "carries;" Avestan baraiti "carries;" Old Persian barantiy "they carry;" Armenian berem "I carry;" Greek pherein "to carry;" Old Irish beru/berim "I catch, I bring forth;" Gothic bairan "to carry;" Old English and Old High German beran, Old Norse bera "barrow;" Old Church Slavonic birati "to take;" Russian brat' "to take," bremya "a burden").