tegmentum
noun
teg·men·tum teg-ˈmen-təm 
plural tegmenta teg-ˈmen-tə
: an anatomical covering : tegmen
especially : the part of the ventral midbrain above the substantia nigra formed of longitudinal white fibers with arched transverse fibers and gray matter
Word History
Etymology
New Latin, from Latin tegumentum, tegmentum, covering, from tegere
First Known Use
1832, in the meaning defined above
Medical Definition
tegmentum
noun
teg·men·tum teg-ˈment-əm
plural tegmenta -ˈment-ə
: an anatomical covering : tegmen
especially : the part of the ventral midbrain above the substantia nigra formed of longitudinal white fibers with arched transverse fibers and gray matter