Each synonyms box has a title with the input word, its part of speech and the root word from which it is derived. Within these major meaning groups, the program displays lists of words:

• ☑ whose meaning is very similar to one another (synonyms),
• ☒ have opposite meaning (antonyms),
• ☐ are related words and expressions.

This Spanish Thesaurus:

1. Shows all possible interpretations of a given word so you can resolve ambiguities and obtain the right set of synonyms which correspond to the intended interpretation.
2. Provides synonyms and antonyms in the same grammatical form as the given word, thus it is an inflected thesaurus.
3. It shows the part of speech and the root words from which the given word can be derived; for example, the word "suma" can be the noun "suma" (addition), or can come from the verb "sumar" (to add), or from the the verb "sumir" (to submerge), or from the adjective "sumo" (ultimate).

Since the same word can have multiple interpretations, the synonyms for each interpretation are different.
The program groups its synonyms according to each grammatical interpretation and presents them in a separate text box.
You can enter an inflected word to this thesaurus and it will show you its synonyms in the same grammatical form as the given word.
For example, if you search for "librito", which is the diminutive of "libro, you will get "... manualcito, textito, volumencito..." which are also diminutives.
Not all words can be inflected to the same grammatical category as the given word, in that case they appear in their root or canonical form.

This dictionary contains some 50,000 entries and holds more than 500,000 synonyms, antonyms, related words and related expressions, making it one of the most complete for the Spanish language.
Taking into account the fact that input words can be inflected, it can actually produce synonyms for more than three million words; the resulting inflected synonyms amount to many millions of words.

This thesaurus contents were used verbatim for many years by Microsoft Office and later licenced to Microsoft in perpetuity so they can use it as their own.