Below is the definition from the product document page.
Search Terms - Define a segment according to a prospect’s search terms.
Using search terms seems like one of the strongest capabilities of RTP. Segmenting and personalizing on intent based search terms allows us to create a great journey.
For example, we use a lot of paid search ads and drive visitors to our landing pages. However, it would be great to customize the heading and intro content based on visitors searching and then clicking on of our ads.
The problem is that for some reason we are seeing next to no traffic from Google paid search, only Yahoo and Bing. The odd things is we see some, just very small numbers. We know this is not correct because 90% of our paid clicks come from Google.
So, how can this be addressed? Thanks for looking!
Several years back Google announced a policy change and started stripping search keywords from all their referral URLs. That is, they stopped sharing them with us publishers.
This incredibly useful data is now known only to Google, or in aggregate (non-"PII") form in Webmaster tools.