An onion dome (Russian: ?????????? ?????, lúkovichnaya glava) is a dome whose shape resembles an onion. Such domes are often larger in diameter than the drum upon which they are set, and their height usually exceeds their width. These bulbous structures taper smoothly to a point.
It is the predominant form for church domes in Russia (Russian: ?????????? ?????, lúkovichnaya glava; mostly on Russian Orthodox churches) and Bavaria, Germany (German: Zwiebelturm (= "onion tower"), plural: Zwiebeltürme, mostly on Catholic churches), but can also be found regularly across Austria, northeastern Italy, Eastern Europe, Mughal India, the Middle East and Central Asia.
Other types of Orthodox cupolas are helmet domes (for example, those of the Saint Sophia Cathedral in Novgorod and Assumption Cathedral in Vladimir), Ukrainian pear domes (Saint Sophia Cathedral in Kiev), and Baroque bud domes (St. Andrew's Church in Kiev).
Onion domes of Cathedral of the Annunciation, Moscow Kremlin.
Detail of onion domes on Saint Basil's Cathedral in Moscow
'My Zwiebelturm (circa 1943) caused me to rush through this article as I had to take a leek.