What Are Synonyms and Antonyms?

Synonyms are different words (spelled and pronounced differently) that have either the exact same meaning or that mean something very similar.

A few examples:

short and diminutive

correct and rectify

buy and purchase

lend and bestow

Antonyms are different words that have either the exactly opposite meaning or an almost exactly opposite meaning.

A few examples:

young and old

active and inactive

tall and short

love and hate

Synonym and antonym, in fact, are antonyms of each other.

Why Use Synonyms or Antonyms?

Synonyms and antonyms can come in handy when you're trying to diversify your diction. If you are writing an essay, and stall at a certain point because you can't think of an exact word, simply use a thesaurus (which is basically a dictionary ordered in terms of synonyms).

Synonyms are also wonderful for gaining an understanding about the relationship between various words, and their precise meaning. I find the notion that love and hate are complete opposites, for example, to be very haunting.

Broader Usage

You might have come across instances where writers used the term "synonymous" in order to draw a connection between two words, ideas, or persons. For example, a reporter might state that "Las Vegas has become synonymous with gambling."

Las Vegas and gambling, unlike, for example, buy and purchase, don't have any inherent connection on a purely linguistic level, but there is an undeniable connection based on the city's image and one of its major industries. The reporter can make that connection because for many people, Las Vegas is indeed strongly associated with the gambling industry. Other similar examples include: New York and skyscrapers, Los Angeles/Hollywood and movies, Paris and romance.

Things to Remember

Not everything can be a synonym or antonym, and you should approach synonyms and antonyms with caution. Do not automatically replace a word with one of its synonyms simply in order to find a different word. Take the example of "buy" and "purchase":

I'm not purchasing it.

I'm not buying it.

"Buy" has several meanings which purchase does not have. In the example above, "buying" can mean "believe", which has nothing to do with any monetary exchange. Examples of this sort can cause your readers confusion, so be careful when resorting to synonyms or antonyms.