Biventral

a. [ L. ventralis, fr. venter the belly; perhaps akin to G. wanst: cf. F. ventral. ] 1. (Anat.) Of, pertaining to, or situated near, the belly, or ventral side, of an animal or of one of its parts; hemal; abdominal; as, the ventral fin of a fish; the ventral root of a spinal nerve; -- opposed to dorsal. [ 1913 Webster ]

2. (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 dorsal. [ 1913 Webster ]

Ventral fins (Zool.), 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. [ 1913 Webster ]