This is a paper in a series to study vertex algebra-like structures arising from various algebras including quantum affine algebras and Yangians. In this paper, we study notions of -adic nonlocal vertex algebra and -adic (weak) quantum vertex algebra, slightly generalizing Etingof-Kazhdan's notion of quantum vertex operator algebra. For any topologically free C[[ ]]-module W , we study -adically compatible subsets and -adically S-local subsets of (EndW )[[x, x −1 ]]. We prove that any -adically compatible subset generates an -adic nonlocal vertex algebra with W as a module and that any -adically S-local subset generates an -adic weak quantum vertex algebra with W as a module. A general construction theorem of -adic nonlocal vertex algebras and -adic quantum vertex algebras is obtained. As an application we associate the centrally extended double Yangian of sl 2 to -adic quantum vertex algebras.