antonym

The English language (and, we may presume, many other languages) has both antonyms and synonyms. There are many more words with synonyms than there are words with antonyms, since many things exist which do not have an opposite (the word sandwich, for instance, may be said to have synonyms in the words hoagie, grinder, submarine, and many other words, but there is no opposite of sandwich). Antonym is also a much more recent addition to English than synonym is; it first appeared in the 1860s, whereas synonym has been used for more than 500 years. Additionally, both nouns have adjectival forms: synonymous and antonymous. Synonymous, which is often used loosely ("She has become synonymous with good taste"), is the more common of the two.