-obverse-

n. [ Cf. F. obverse, obvers. See Obverse, a. ] 1. The face of a coin which has the principal image or inscription upon it; -- the other side being the reverse. [ 1913 Webster ]

2. Anything necessarily involved in, or answering to, another; the more apparent or conspicuous of two possible sides, or of two corresponding things. [ 1913 Webster ]

The fact that it [ a belief ] invariably exists being the obverse of the fact that there is no alternative belief. H. Spencer. [ 1913 Webster ]