The English language contains a wealth of words, and perhaps no other language has as many synonyms as English. Synonyms give color, precision, and variety to a person's writing, breaking up the dullness that can come from too many overused words.

So, just what are synonyms? Put simply, synonyms are words that mean the same thing. Words that are only somewhat similar in meaning—but do not mean the same thing—are not true synonyms. They are merely related words, and they belong in a different category.

In this thesaurus a word is classified as a synonym if and only if it shares with another word at least one basic meaning. Here's an example of how we arrived at a basic meaning shared by one group of words. The word freight is defined in Merriam-Webster's Intermediate Dictionary as "goods or cargo carried by ship, train, truck, or airplane." We can break up the definition like this:

Since a person using freight as the starting point in his or her search for the right word is probably dissatisfied with that term, the word that he or she is seeking will most likely come under a broader or more basic meaning. We can phrase that more basic meaning as: "a mass or quantity of something taken up and carried, conveyed, or transported." The list of synonyms for freight—burden, cargo, draft, haul, lading, load, loading, payload, weight—can all be said to share this basic meaning.

If a word is more limited in scope than the basic meaning given at a main entry, then it cannot be regarded as a synonym. Hence, truckload, which refers specifically to the load carried by a truck, cannot be a synonym of freight and the other members of freight's synonym group. Likewise, the words mass and quantity cannot themselves be regarded as synonyms because the notion of being carried, conveyed, or transported is not an essential part of their meaning.

If a word is used as the defining term in a shared meaning, it will not be listed as one of the synonyms. Since words can only be defined in terms of other words, the result of this restriction is that some terms that might be rightly regarded as synonyms do not appear in the synonym lists. Here is an example:

Entry Word: go
Function: verb
Text: . . .
2 to leave a place often for another <will go on vacation at the end of the year> <decided it would be better to go before she got any angrier>
Synonyms: begone, clear out, depart, exit, get, get off, move, pull (out), quit, sally (forth), shove (off), take off, walk out

Leave, used as the defining term, could be considered another synonym, but it is not entered as such in this thesaurus because it has been used as a defining term.