onion dome noun

A bulb-shaped dome having a sharp point, characteristic of Eastern Orthodox, esp Russian, church architecture

onˈion-eyed adjective (Shakespeare)

Having the eyes full of tears

onion fly noun

An insect, Delia antiqua, whose larvae are a serious pest of onions

onˈion-skin noun

A very thin variety of paper

know one's onions (informal)

To know one's subject or job well

off one's onion (slang)

Off one's head