1. nearest to or facing toward the axis of an organ or organism

e.g. the upper side of a leaf is known as the adaxial surface

Synonym: adaxial

2. toward or on or near the belly (front of a primate or lower surface of a lower animal)

e.g. the ventral aspect of the human body
the liver is somewhat ventral in position
ventral (or pelvic) fins correspond to the hind limbs of a quadruped