The Collaborative International Dictionary
Mesial plane
Mesial \Me"sial\ (?; 277), a. [Gr. me`sos middle.] (Anat.) Middle; median; in, or in the region of, the mesial plane; internal; -- opposed to lateral.
Mesial plane. (Anat.) See Meson.
Wiktionary
mesial plane
n. (context anatomy English) the plane which divides the body of an animal into similar right and left halves