From The Free On-line Dictionary of Computing: (http://www.foldoc.org/, Editor Denis Howe)
/sheir'weir/ Software that, like freeware, can be usually obtained (downloaded) and redistributed for free, but most often is under copyright and does legally require a payment in the EULA, at least beyond the evaluation period or for commercial applications. This payment, as well as fulfilling the user's legal obligations, may buy additional support, documentation, or functionality. Generally, source code for shareware programs is not available. Shareware is sometimes also nagware and/or crippleware, which muddles the term and is frowned upon in the community.