The Collaborative International Dictionary of English v.0.48:

Confessional \Con*fes"sion*al\, n. [F. confessional.]
   The recess, seat, or inclosed place, where a priest sits to
   hear confessions; often a small structure furnished with a
   seat for the priest and with a window or aperture so that the
   penitent who is outside may whisper into the priest's ear
   without being seen by him or heard by others.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Confessional \Con*fes"sion*al\, a.
   Pertaining to a confession of faith.
   [1913 Webster]

   Confessional equality, equality before the law of persons
      confessing different creeds.
      [1913 Webster]

WordNet (r) 3.0 (2006):

confessional
    n 1: a booth where a priest sits to hear confessions

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "confessional":
   Easter sepulcher, admissive, ambry, apse, baptistery, blindstory,
   canonical, chancel, choir, cloisters, confessionary, creedal,
   crypt, diaconicon, diaconicum, doctrinal, dogmatic, nave, porch,
   presbytery, rood loft, rood stair, rood tower, sacrarium, sacristy,
   transept, triforium, vestry