treey

This doesn't happen often within word boundaries, but a crappy, but sufficiently illustrative example might be adding the productive adjectival suffix "-y" to a noun like "tree", making "treey".

On /r/s and ofs DC 2008

The problem with wi-fi links in my area of the country 60 miles south of St. Louis, is the terrain is just hilly and “treey” enough that even when placing access points on hills, you don’t get a lot of coverage.

Slow road to rural broadband 2005