The common Cornish prefix TRE means hamlet or farming settlement and possibly having pre-Norman origins circa 500 A.D. it is not normally used later than 1100 and indicates early occupation of the site. The suffix WAUN (old Welsh) means meadow or down hence the name Trowan probably describes a settlement or habitation "in the meadow".
Well of course they're the same jno, I'd just seen yours! :0)
I only clicked on cause it said Cornwall and I thought it might be about the little festival down there last weekend. Then I got confused cause I couldn't see your answer.