n 1 a  :  a surface that contains at least three points not all in a straight line and is such that a line drawn through any two points in it lies wholly in the surface  b  :  an imaginary plane used to identify parts of the body or a part of the skull - see FRANKFORT HORIZONTAL PLANE MIDSAGITTAL PLANE   2  :  a stage in surgical anesthesia <a light of anesthesia is maintained with cyclopropane -Jour. Amer. Med. Assoc.>  .
 
 
 
Similar sounding terms:  plana  pla·no  pol·len  py·lon 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2004.