The Collaborative International Dictionary of English v.0.48:

Parquet circle \Parquet circle\
   That part of the lower floor of a theater with seats at the
   rear of the parquet and beneath the galleries; -- called
   also, esp. in U. S., orchestra circle or parterre.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Parterre \Par*terre"\, n. [F., fr. par on, by (L. per) + terre
   earth, ground, L. terra. See Terrace.]
   1. (Hort.) An ornamental and diversified arrangement of beds
      or plots, in which flowers are cultivated, with
      intervening spaces of gravel or turf for walking on.
      [1913 Webster]

   2. The pit of a theater; the parquet. [France]
      [1913 Webster]

WordNet (r) 3.0 (2006):

parterre
    n 1: an ornamental flower garden; beds and paths are arranged to
         form a pattern
    2: seating at the rear of the main floor (beneath the balconies)
       [syn: parquet circle, parterre]

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "parterre":
   auditorium, balcony, billiard table, bowling green, box, box seat,
   dead flat, dead level, dress circle, earth, esplanade, fauteuil,
   flat, flatland, floor, gallery, ground, homaloid, horizontal,
   horizontal axis, horizontal fault, horizontal line,
   horizontal parallax, horizontal plane, horizontal projection,
   ledge, level, level line, level plane, loge, mean sea level,
   nigger heaven, orchestra, orchestra circle, paradise, parquet,
   parquet circle, peanut gallery, pit, plain, plane, platform,
   prairie, proscenium boxes, sea level, sea of grass, stall,
   standing room, steppe, table, terrace, theatre stall,
   water level