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Nov 12, 2018
Nov 12, 2018

About Hunspell

Hunspell is a free spell checker and morphological analyzer library and command-line tool, licensed under LGPL/GPL/MPL tri-license.

Hunspell is used by LibreOffice office suite, free browsers, like Mozilla Firefox and Google Chrome, and other tools and OSes, like Linux distributions and macOS. It is also a command-line tool for Linux, Unix-like and other OSes.

It is designed for quick and high quality spell checking and correcting for languages with word-level writing system, including languages with rich morphology, complex word compounding and character encoding.

Hunspell interfaces: Ispell-like terminal interface using Curses library, Ispell pipe interface, C++/C APIs and shared library, also with existing language bindings for other programming languages.

Hunspell's code base comes from's MySpell library, developed by Kevin Hendricks (originally a C++ reimplementation of spell checking and affixation of Geoff Kuenning's International Ispell from scratch, later extended with eg. n-gram suggestions), see, and its README, CONTRIBUTORS and license.readme (here: license.myspell) files.

Main features of Hunspell library, developed by László Németh:

  • Unicode support
  • Highly customizable suggestions: word-part replacement tables and stem-level phonetic and other alternative transcriptions to recognize and fix all typical misspellings, don't suggest offensive words etc.
  • Complex morphology: dictionary and affix homonyms; twofold affix stripping to handle inflectional and derivational morpheme groups for agglutinative languages, like Azeri, Basque, Estonian, Finnish, Hungarian, Turkish; 64 thousand affix classes with arbitrary number of affixes; conditional affixes, circumfixes, fogemorphemes, zero morphemes, virtual dictionary stems, forbidden words to avoid overgeneration etc.
  • Handling complex compounds (for example, for Finno-Ugric, German and Indo-Aryan languages): recognizing compounds made of arbitrary number of words, handle affixation within compounds etc.
  • Custom dictionaries with affixation
  • Stemming
  • Morphological analysis (in custom item and arrangement style)
  • Morphological generation
  • SPELLML XML API over plain spell() API function for easier integration of stemming, morpological generation and custom dictionaries with affixation
  • Language specific algorithms, like special casing of Azeri or Turkish dotted i and German sharp s, and special compound rules of Hungarian.

Main features of Hunspell command line tool, developed by László Németh:

  • Reimplementation of quick interactive interface of Geoff Kuenning's Ispell
  • Parsing formats: text, OpenDocument, TeX/LaTeX, HTML/SGML/XML, nroff/troff
  • Custom dictionaries with optional affixation, specified by a model word
  • Multiple dictionary usage (for example hunspell -d en_US,de_DE,de_medical)
  • Various filtering options (bad or good words/lines)
  • Morphological analysis (option -m)
  • Stemming (option -s)

See man hunspell, man 3 hunspell, man 5 hunspell for complete manual.


Build only dependencies:

g++ make autoconf automake autopoint libtool

Runtime dependencies:

Mandatory Optional
hunspell tool libiconv gettext ncurses readline

Compiling on GNU/Linux and Unixes

We first need to download the dependencies. On Linux, gettext and libiconv are part of the standard library. On other Unixes we need to manually install them.

For Ubuntu:

sudo apt install autoconf automake autopoint libtool

Then run the following commands:

autoreconf -vfi
sudo make install
sudo ldconfig

For dictionary development, use the --with-warnings option of configure.

For interactive user interface of Hunspell executable, use the --with-ui option.

Optional developer packages:

  • ncurses (need for --with-ui), eg. libncursesw5 for UTF-8
  • readline (for fancy input line editing, configure parameter: --with-readline)

In Ubuntu, the packages are:

libncurses5-dev libreadline-dev

Compiling on OSX and macOS

On macOS for compiler always use clang and not g++ because Homebrew dependencies are build with that.

brew install autoconf automake libtool gettext
brew link gettext --force

Then run autoreconf, configure, make. See above.

Compiling on Windows

Compiling with Mingw64 and MSYS2

Download Msys2, update everything and install the following packages:

pacman -S base-devel mingw-w64-x86_64-toolchain mingw-w64-x86_64-libtool

Open Mingw-w64 Win64 prompt and compile the same way as on Linux, see above.

Compiling in Cygwin environment

Download and install Cygwin environment for Windows with the following extra packages:

  • make
  • automake
  • autoconf
  • libtool
  • gcc-g++ development package
  • ncurses, readline (for user interface)
  • iconv (character conversion)

Then compile the same way as on Linux. Cygwin builds depend on Cygwin1.dll.


It is recommended to install a debug build of the standard library:


For debugging we need to create a debug build and then we need to start gdb.

./configure CXXFLAGS='-g -O0 -Wall -Wextra'
./libtool --mode=execute gdb src/tools/hunspell

You can also pass the CXXFLAGS directly to make without calling ./configure, but we don't recommend this way during long development sessions.

If you like to develop and debug with an IDE, see documentation at


Testing Hunspell (see tests in tests/ subdirectory):

make check

or with Valgrind debugger:

make check
VALGRIND=[Valgrind_tool] make check

For example:

make check
VALGRIND=memcheck make check


features and dictionary format:

man 5 hunspell
man hunspell
hunspell -h


After compiling and installing (see INSTALL) you can run the Hunspell spell checker (compiled with user interface) with a Hunspell or Myspell dictionary:

hunspell -d en_US text.txt

or without interface:

hunspell -d en_GB -l <text.txt

Dictionaries consist of an affix (.aff) and dictionary (.dic) file, for example, download American English dictionary files of LibreOffice (older version, but with stemming and morphological generation) with

wget -O en_US.aff
wget -O en_US.dic

and with command line input and output, it's possible to check its work quickly, for example with the input words "example", "examples", "teached" and "verybaaaaaaaaaaaaaaaaaaaaaad":

$ hunspell -d en_US
Hunspell 1.7.0

+ example

& teached 9 0: taught, teased, reached, teaches, teacher, leached, beached

# verybaaaaaaaaaaaaaaaaaaaaaad 0

Where in the output, * and + mean correct (accepted) words (* = dictionary stem, + = affixed forms of the following dictionary stem), and & and # mean bad (rejected) words (& = with suggestions, # = without suggestions) (see man hunspell).

Example for stemming:

$ hunspell -d en_US -s
mice mouse

Example for morphological analysis (very limited with this English dictionary):

$ hunspell -d en_US -m
mice  st:mouse ts:Ns

cats  st:cat ts:0 is:Ns
cats  st:cat ts:0 is:Vs

Other executables

The src/tools directory contains the following executables after compiling.

  • The main executable:
    • hunspell: main program for spell checking and others (see manual)
  • Example tools:
    • analyze: example of spell checking, stemming and morphological analysis
    • chmorph: example of automatic morphological generation and conversion
    • example: example of spell checking and suggestion
  • Tools for dictionary development:
    • affixcompress: dictionary generation from large (millions of words) vocabularies
    • makealias: alias compression (Hunspell only, not back compatible with MySpell)
    • wordforms: word generation (Hunspell version of unmunch)
    • hunzip: decompressor of hzip format
    • hzip: compressor of hzip format
    • munch (DEPRECATED, use affixcompress): dictionary generation from vocabularies (it needs an affix file, too).
    • unmunch (DEPRECATED, use wordforms): list all recognized words of a MySpell dictionary

Example for morphological generation:

$ ~/hunspell/src/tools/analyze en_US.aff en_US.dic /dev/stdin
cat mice
generate(cat, mice) = cats
mouse cats
generate(mouse, cats) = mice
generate(mouse, cats) = mouses

Using Hunspell library with GCC

Including in your program:

#include <hunspell.hxx>

Linking with Hunspell static library:

g++ -lhunspell-1.7 example.cxx
# or better, use pkg-config
g++ $(pkg-config --cflags --libs hunspell) example.cxx


Hunspell (MySpell) dictionaries:

Aspell dictionaries (conversion: man 5 hunspell):


László Németh, nemeth at numbertext org