If you talking about Internal Search Keywords, then you can take my comment below.
First, you need to understand the dimension type: Whether it is an evar or a Prop. If it is an eVar, then you just use the eVar with eVar Instances or Event (If you have an assigned event) to understand which keyword searched the most.
Considering you have Prop to capture the keyword then it will have Exit Keyword as a separate dimension, but I don't think that will give the Search Keyword that leads to visitor exit because Entry and Entry dimension didn't mean the first hit or last hit, rather the first set dimension and last set dimensional value. Check out my take on Entry Dimensions & Entries Metric: Click Here. So, if you ask me, Exit Keyword searched will not yield you the results you want.
But, if you have a separate Page or firing Page Name for Search Results Page, then correlate the Page Exits or Page Bounces by Keyword to see the results you want.