aspell – Spell checker

GNU Aspell is a Free and Open Source spell checker designed to replace Ispell. It can either be used as a library or as an independent spell checker. Its main feature is that it does a superior job of suggesting possible replacements for a misspelled word than just about any other spell checker out there for the English language. Aspell can check documents in UTF-8 without having to use a special dictionary; and will do its best to respect the current locale setting.

A wide range of language-specific dictionaries is available.