A definition could be: the rights a creator of a literary, artistic or scientific work has to enforce their authorship and prohibit or authorise others to use her work.
The legislations of almost all countries do recognize that authors have several rights upon their works. Generally speaking, thanks to those rights authors can decide whether their works can be reproduced, translated, distributed or not, and the terms in which they can be used, broadcasted or modified.
Continental Law Systems recognizes two kind of basic rights, moral and economic.
Moral rights, with possible variations from one legislation to another, relate to the right to be credited or mentioned as the author of the work, the right to decide if the work might be disseminate, if it will be disseminated with the real name or pseudonym, the right to enforce the integrity of the creation, the right to withdraw the work of trade, right to retract or repent, right to access to the unique copy...
In many legislations, such the Spanish one, moral rights are unalienable and cannot be waived.
Economic rights are the rights who provide royalties to the creator and can be transferred, so the author has to authorize anyone the reproduction or performance of each work, so to say, the possibility to copy, record, public performance, broadcasting or transform it.
A legal post explaining the Cppyrigt Scope: moral and economic rights is available at http://en.safecreative.net/2008/11/19/copyright-scope-moral-and-economic-rights/.