Acolyte

acolyte
    n 1: someone who assists a priest or minister in a liturgical
         service; a cleric ordained in the highest of the minor
         orders in the Roman Catholic Church but not in the Anglican
         Church or the Eastern Orthodox Churches
    

Acolyte \Ac`o*lyte\, n. [LL. acolythus, acoluthus, Gr. ?
   following, attending: cf. F. acolyte.]
   [1913 Webster]
   1. (Eccl.) One who has received the highest of the four minor
      orders in the Catholic church, being ordained to carry the
      wine and water and the lights at the Mass.
      [1913 Webster]

   2. One who attends; an assistant. "With such chiefs, and with
      James and John as acolytes." --Motley.
      [1913 Webster]
    

altar boy \al"tar boy\, n.
   a boy who assists a priest at the clebration of the Holy Mass
   and other forms of public worship; -- also called {acolyte}.
   [PJC]
    

75 Moby Thesaurus words for "acolyte":
      Bible clerk, Bible reader, acolytus, adjutant, agent, aid, aide,
      aide-de-camp, aider, almoner, anagnost, assistant, attendant,
      auxiliary, beadle, bedral, best man, capitular, capitulary,
      choir chaplain, churchwarden, clerk, coadjutant, coadjutor,
      coadjutress, coadjutrix, deacon, deaconess, deputy, diaconus,
      doorkeeper, elder, elderman, executive officer, exorcist,
      exorcista, help, helper, helpmate, helpmeet, holy orders,
      lay elder, lay reader, lector, lecturer, lieutenant, major orders,
      minor orders, ostiarius, paranymph, paraprofessional, parish clerk,
      precentor, presbyter, priest, reader, ruling elder, sacrist,
      sacristan, second, servant, sexton, shames, sideman, sidesman,
      subdeacon, subdiaconus, succentor, suisse, supporting actor,
      supporting instrumentalist, teaching elder, thurifer, verger,
      vergeress