fellow traveller

Noun

fellow traveller (plural fellow travellers)

1. One who travels together with another.
   • The arrangement of some seats facing and some one behind the other, bus fashion, seems a sensible compromise; I am one of those who do not enjoy staring at my fellow travellers for perhaps hours on end.1964 July, Mary Allen, “A Woman's View of the New Coaches”, in Modern Railways, page 9
2. One who sympathizes with the aims or beliefs of an organization without belonging to it; especially a Communist sympathizer.
   • Near-synonym: camp follower
   • Earlier in the year, Ohio Senator Robert Taft charged that Democratic congressional proposals "bordered on communism," while Joe Martin called for Republican victories in order to oust the Communists and fellow travelers from the federal government.1978, Richard Nixon, RN: the Memoirs of Richard Nixon, Grosset & Dunlap, →ISBN, →LCCN, →OCLC, →OL, page 42

   Synonyms:

   camp follower