Definitions for Enhancement
an improvement that makes something more agreeable
the act of increasing, or state of being increased; augmentation; aggravation; as, the enhancement of value, price, enjoyments, crime
The New Hacker's Dictionary
Common marketroid-speak for a bug fix. This abuse of language is a popular and time-tested way to turn incompetence into increased revenue. A hacker being ironic would instead call the fix a feature — or perhaps save some effort by declaring the bug itself to be a feature.