About Stop Words

Stop words are typically very common words considered to carry less meaning such as articles, prepositions, and pronouns. By default, all Coveo search results contain all searched terms, but the Coveo ranking algorithm considers very frequent terms to carry less meaning and their presence in an item does not significantly increase the item ranking.

You can however add stop words that you want to ignore from queries if you see they can impact ranking and search results.

When stop words are defined, they are removed from a query entered by a user before it is sent to the index which allows item not containing the stop words to be included in the results, increases the importance of other keywords, and help getting more relevant search results.

A user enters the following natural language query:

The common words do, I, my, for, and the will contribute to restrict return search results and dilute the most meaningful keywords of the query (change, password, and intranet).

When these common terms are included in the stop word rules, the query sent to the index is:

how change password intranet

The search results for only these four keywords will most likely include more relevant items.

Stop Words Special Cases

The stop words management rule is simple. Stop words are removed only when they are part of an AND (explicit or implicit) or OR expression, or sub-expression. Stop words are not removed when they occur alone, because otherwise the removal could create an invalid expression.

The Coveo Cloud Platform indexes all terms contained in your source items, including the stop words. This allows the Coveo Platform to manage exceptions and keep stop words in the query in the following cases:

  • The condition associated to a stop word rule is not fulfilled.

    Since you applied the Language is en_US condition on your stop word rule, the common word it contains will not be removed if present in a query from a user in Germany.

  • Stop words within a phrase search.

    A user is looking for an item that contains a very specific phrase and encloses the phrase between double-quotes in the search box:

    Even if the common terms in, the, and for are stop words, all keywords of this query are sent to the index, so only items containing same order contiguous occurrences of these keywords are returned.

  • A query containing only stop words.

    A user searches for:

    If all the keywords of this query are stop words, they are all kept and sent to the index.

  • A stop word is an argument of the NOT or NEAR operators.

    • A user searches for:

      If how is a stop word, because it is an argument of the NEAR operator, it will be kept to return items containing both how and export occurring within ten terms from each other.

    • A user searches for:

      If how is a stop word, because it is an argument of the NOT operator, and the NOT operator has precedence over the implicit AND operator, it will be kept to return items containing both how and export.

What’s Next?

Learn which words should be stop words (see Stop Words Leading Practices).