Aquamacs 2.0 and onwards uses the Mac OSX spell-checking system. (Alternative spelling engines can be configured.)
Aquamacs 1.9 provides advanced spell-checking with high-quality dictionaries in more than 85 languages.
Spell-Checking is distributed separately from the main download, so you only need to download and install the dictionaries that you actually need. (If you already have Aspell or Ispell installed, e.g. via MacPorts, Aquamacs will automatically use that program and its dictionaries for spell-checking.)
You can either install
Or, just install
Installer packages designed by Anton Leuski at USC. Aspell is a spell-checking engine provided by the GNU Project. If you can produce installer packages for other languages, please help the Aquamacs project by contributing.