"terraqin" is one letter from "terrain". "terraqin" has very few citations on the web. "terraqin" is an easy mispelling of "terrain" on a QWERTY keyboard, you can 'fat finger' "q" and "a" together.

Google is totally correct to assume you meant "terrain" for now. That's the smoother user experience for the majority of users.

When 'TeRraQin' (horrible capitalisation by the way) has more web-based citations Google will automatically start serving better results.

In fact this HN post is already showing in the SERPs.