What does "ventral" mean?

Ventral: (Bot.) (a) Of or pertaining to that surface of a carpel, petal, etc., which faces toward the center of a flower. (b) Of or pertaining to the lower side or surface of a creeping moss or other low flowerless plant. Opposed to Ant: dorsal. Ventral fins (Zoöl.), the posterior pair of fins of a fish. They are often situated beneath the belly, but sometimes beneath the throat. -- Ventral segment. (Acoustics) See Loop, n., 5.