principal vertical circle
principal vertical circle
[′prin·sə·pəl ′vərd·ə·kəl ‚sər·kəl] (geodesy)
The vertical circle through the north and south points of the horizon, coinciding with the celestial meridian.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.