How to use a thesaurus without making your writing worse

A thesaurus is most useful for finding a word you already half know, the one on the tip of your tongue, and least useful for making plain writing sound clever. Use it to gather candidates, then check each one against your sentence for meaning, tone and fit before you swap it in. The synonym finder is the thesaurus I built for this site; this guide covers how to use it, or any thesaurus, well.

Why synonyms are not interchangeable

True synonyms, words that could replace each other in every sentence with no change in meaning, are rare. Words grouped together in a thesaurus, since Peter Mark Roget published the first famous one in 1852, overlap in one sense but differ in others:

• Connotation: thrifty, frugal and stingy all describe spending little, but only one is an insult.
• Register: angry is neutral, irate is formal, livid is emphatic, and cross is milder and more British.
• Strength: dislike, loathe and detest sit at different points on the same scale.
• Collocation: words have habitual partners. We say heavy rain and strong tea; weighty rain and powerful tea sound wrong even though the meanings are close.
• Grammar: rely needs on, while trust takes a direct object, so swapping a verb can break the sentence around it.

A five-step method

• Name the problem first. Is the word repeated, vague, too formal, or not quite accurate? The answer decides what you are looking for.
• Scan beyond the first result. The right word is often a few places down the list.
• Check the sense. If your word has several meanings, make sure the synonym belongs to the one you used.
• Look up anything unfamiliar in a dictionary, including its example sentences. If you have never seen a word used, your reader may not have either.
• Read the sentence aloud with the new word in it. If it sounds like a thesaurus wrote it, go back to the original or rewrite the sentence.

A worked example

Take a draft line: "The team walked to the summit after a long day." Suppose walked feels flat. A thesaurus offers strolled, marched, trudged, ambled and hiked, and each tells a different story. Strolled and ambled say the team was relaxed, which contradicts "after a long day". Marched suggests discipline or determination. Hiked is accurate but adds little. Trudged says they were tired, which fits. The best choice is trudged, not because it is fancier but because it carries information the original did not. That is the test: a good synonym makes the sentence more exact, not just more varied.

Common pitfalls

The best-known trap has a name. H. W. Fowler called it elegant variation: changing a word only to avoid repeating it, so that a house becomes a dwelling and then a residence in successive sentences. Readers start to wonder whether three different buildings are involved. In technical, legal and instructional writing, repeating the key term is a feature, not a fault.

The second trap is reaching for longer, rarer words to sound more serious. Utilise for use and commence for start usually make writing harder to read, and the readability checker will show it as a lower score. The third is ignoring which sense the thesaurus is giving you: light meaning not heavy and light meaning bright have entirely different synonyms.

How the synonym finder works

The synonym finder draws on Moby Thesaurus II, a large public-domain thesaurus compiled by Grady Ward, trimmed to about 25,000 headwords with up to 30 synonyms each. Rather than listing them alphabetically, it ranks them by meaning overlap: synonyms that share many of their own synonyms with your word are treated as the same sense and come first, so the top ten are usually the closest matches. Inflected words are mapped to a base form, so running looks up run and happier looks up happy, and clicking any result explores its synonyms, with a trail of where you have been.

Its limits are worth knowing. Different senses of a word are mixed into one list, so step three above still applies. The source dates from the 1990s and is American English, so some modern senses and slang are missing, and it does not list antonyms. Nothing you type is sent anywhere; only the small word file for your word's first letter loads from the site.

When to skip the thesaurus

Often the real fix is the sentence, not the word. If you keep repeating a word, the word frequency counter shows how often each one appears, and the answer may be to merge two sentences or use a pronoun. If a word feels weak because it leans on very or really, cutting the intensifier helps more than a synonym, as Filler words to cut from your writing, and when to keep them explains. If a phrase feels tired, it may be a cliché that needs a specific detail instead; Clichés to avoid in writing, and what to write instead covers those. And for poems and lyrics, pairing the thesaurus with the rhyme finder helps you find a word that fits both the sound and the sense.