|credit: Christian Pfeiffer|
<Advent> is pronounced /ˈædvent/ or /ˈædv(ə)nt/. It's of Latin origin: advenīre as a verb meaning 'to arrive' and the Latin noun adventus 'arrival'.
What's in a wreath etymologically? OED tells us that it's derived from Old English wriþan 'to twist, coil'.
The plural <wreaths> is pronounced /riːðz/ or /riːθs/.
The history of the advent wreath, its spread from the Old to the New World is interesting but beyond the scope of this blog. Mary Jane Haemig, associate professor at Luther Seminary, St. Paul, Minnesota, published an article in 2005 on "The Origin and Spread of the Advent Wreath", Lutheran Quarterly 19,3: 332-343, in which she shows that the advent wreath became popular in 19th century Germany and entered the American Lutheran practice in the early 20th century.