posterior

adjective

(L. posterior: behind, last, posterior) Of floral parts, on the side of the flower nearest to the axis, as the upper lip of a bilabiate corolla; in transversely inserted leaves, the side or surface oriented toward the axis.
For most animals, the end opposite the head.
Posterior for bivalves: The end of the shell where the siphons are located, opposite the end with the head and foot (photo). Often most easily identified by the posterior location of the pallial sinus, or by the fact that the hinge ligament is usually posterior to the umbo.
Cf. anterior.