Spell checker and custom dictionaries for your thesis, in any language

Updated 18 October 2026 · overminder

Proper names, technical terms and foreign words drive spell checkers mad. A good checker and a personal dictionary solve it.

Three levels of checking

1. Spelling: misspelled words.
2. Grammar: agreement, tenses, punctuation.
3. Style: repetition, overlong sentences, register.

The terms of your field

Prepare a plain list of words, one per line, and load it as a dictionary:

georeferencing
Cittaslow
intermodality
walkability

Your own synonyms and antonyms

A CSV table with word, synonyms and antonyms:

word;synonyms;antonyms
fast;quick|rapid;slow
increase;grow|rise;decrease

Or a list of equivalent synonyms, one group per line: evident, clear, obvious.

Standard formats

• Hunspell (.dic + .aff): the dictionaries of LibreOffice, Firefox and Chrome, available for dozens of languages.
• MyThes (.dat): LibreOffice thesauri.
• .oxt and .xpi extensions that contain them.

With Gradus

In Settings → Proofreader and assistant you load dictionaries from a file or a web link, or add the free dictionaries for your language in one click. Those words are no longer flagged by LanguageTool, checking also works offline and synonyms appear in the Assistant panel.