Obverse

Part of speech: noun (n.)

1. The face of a coin which has the principal image or inscription upon it; -- the other side being the reverse.

2. Anything necessarily involved in, or answering to, another; the more apparent or conspicuous of two possible sides, or of two corresponding things. The fact that it [a belief] invariably exists being the obverse of the fact that there is no alternative belief. H. Spencer.

Part of speech: adjective (a.)

Having the base, or end next the attachment, narrower than the top, as a leaf.