Zen Temple
noun
A zen temple is just what it sounds like, a zen temple. Sounds nice.
The reading is the two words 禅 and 寺 put together. The てら gets changed to でら, though.
In terms of when it's pronounced ぜんじ, if you put this word onto the end of the name of a 禅寺 the pronunciation changes to ぜんじ. It makes sense - it's more like a jukugo word that way (not that the original isn't, but you can see the separation of words coming together which gives the hint that it's a kun'yomi combo reading). Anyways, you may need a zen temple to keep your mind pure enough to remember this, but it's a good thing to keep in mind if you can.
あの禅寺の名前は何だっけ？
What's the name of that Zen temple, again?
京都の南禅寺に行ってきました。
I visited Nanzenji temple in Kyoto.
このお寺は、十四世紀に建てられた禅寺です。
This temple is a Zen temple built in the 14th century.
東福寺っていう京都の禅寺が好きなんです。
I like the Zen temple in Kyoto called Tōfuku-ji.