The Collaborative International Dictionary of English v.0.48:

Chapel \Chap"el\, n. [OF. chapele, F. chapelle, fr. LL. capella,
   orig., a short cloak, hood, or cowl; later, a reliquary,
   sacred vessel, chapel; dim. of cappa, capa, cloak, cape,
   cope; also, a covering for the head. The chapel where St.
   Martin's cloak was preserved as a precious relic, itself came
   to be called capella, whence the name was applied to similar
   paces of worship, and the guardian of this cloak was called
   capellanus, or chaplain. See Cap, and cf. Chaplain.,
   Chaplet.]
   1. A subordinate place of worship; as,
      (a) a small church, often a private foundation, as for a
          memorial;
      (b) a small building attached to a church;
      (c) a room or recess in a church, containing an altar.
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   Note: In Catholic churches, and also in cathedrals and abbey
         churches, chapels are usually annexed in the recesses
         on the sides of the aisles. --Gwilt.
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   2. A place of worship not connected with a church; as, the
      chapel of a palace, hospital, or prison.
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   3. In England, a place of worship used by dissenters from the
      Established Church; a meetinghouse.
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   4. A choir of singers, or an orchestra, attached to the court
      of a prince or nobleman.
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   5. (Print.)
      (a) A printing office, said to be so called because
          printing was first carried on in England in a chapel
          near Westminster Abbey.
      (b) An association of workmen in a printing office.
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   Chapel of ease.
      (a) A chapel or dependent church built for the ease or a
          accommodation of an increasing parish, or for
          parishioners who live at a distance from the principal
          church.
      (b) A privy. (Law)

   Chapel master, a director of music in a chapel; the
      director of a court or orchestra.

   To build a chapel (Naut.), to chapel a ship. See Chapel,
      v. t., 2.

   To hold a chapel, to have a meeting of the men employed in
      a printing office, for the purpose of considering
      questions affecting their interests.
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