Hunspell is a widely used spell checker

Main features:
- Extended support for language peculiarities; Unicode character encoding,
  compounding and complex morphology.
- Improved suggestion using n-gram similarity, rule and dictionary based
  pronunciation data.
- Morphological analysis, stemming and generation.
- Hunspell is based on MySpell and works also with MySpell dictionaries.
- C++ library under GPL/LGPL/MPL tri-license.

WWW: http://hunspell.sourceforge.net/