What is Broad match modifier keywords

You can add a modifier, the plus sign on your keyboard (+), to any of the terms that are part of your broad match keyword phrase. By adding a modifier, your ads can only show when someone’s search contains those modified terms, or close variations of the modified terms, in any order. The modifier won’t work with phrase match or exact match keywords.

Unlike broad match keywords, modified broad match keywords won’t show your ad for synonyms or related searches. For this reason, it adds an additional level of control. Using broad match modifier is a good choice if you want to increase relevancy even if it means you might get less ad traffic than broad match.