Other than specifying the keywords for the campaign, Amazon also lets you match the different types of searches - Keyword Match Types. You can decide to display your product ad based on the matches of the search term with your keywords for exact search term match, terms are padded before and after the search terms, make restrictions on the order in which the search terms are displayed, etc.
Your keyword(s) will be matched to search terms that not only match your keyword but are also related to your keyword and your advertisement may display regardless of what order the keywords appear in or what additional words are added. This might include synonyms, misspellings, and variations of your keyword.
https://www.sellerapp.com/help/article/amazon-keyword-match-types/
