Why doesn't the Thesaurus have antonyms?

H

headly

According to dictionary.com:
A book of synonyms, often including related and contrasting words and antonyms
 
O

Office Helper

In Excel 2003, when looking up word in the thesaurus, it list synonyms and
also antonyms. The antonyms are usually listed towards the bottom and say
(antonym) after the word.
 
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