In that case, it's best to go back and narrow your search. A search for cats OR dogs would give results for cats, dogs, and cats plus dogs. NOT is used to exclude keywords from a search. In using the Boolean operator NOT, the results would include the initial keywords only if the keyword excluded by the operator NOT does not appear. A search for cats NOT dogs would produce results that discussed cats, but if that source mentioned dogs, it would not be included in the results of this search.
Truncation is used to retrieve keywords having the same root word.
Be cautious when using truncation on a short root word since results can be unexpected. Truncation can be handy with plurals or different verb tenses. It can be a useful tool when used properly. Wildcards are used to retrieve keywords with variant or uncertain spellings. Just as in truncation, be cautious about using wildcards with short words.