A corenwyn (or corenwijn) is a type of genever:
Genever is a dry spirit made from grains and distilled with herbs such as angelica, coriander, licorice and anise. Genever’s trademark is a marked maltiness combined with a complex but fairly light herbal profile. Like gin, genevers contain juniper, but generally in a much less prominent role. Distillers create their own unique formulas, which are often kept secret.This sounds a lot better than the stupid gifts AdSense had been sending out over the last few years!
Amsterdam pubs stock several types of genevers, the most common of which are jonge, oude, corenwijn and fruit. A general misconception is that oude and jonge genever means aged and unaged. In fact, the names refer to the recipes. Oude genever is an older formula, with a moderate amount of maltiness and botanicals. Younger generations of Dutch drinkers began desiring a smoother, mellower spirit, which led to jonge (young) genever, which is less malty and has a cleaner, more subtle taste, closer to a vodka. Corenwijn (also spelled corenwyn or korenwijn) is the maltiest. There are also fruit genevers—a more modern creation—which downplay the malt and botanicals and have added fruit flavors, such as berries and citrus.
Source: Oude Spirits.