Answer: oculus

AnswerCrossword Clue
OCULUSDome opening, in architecture
OCULUSEye
OCULUS... mundi (opal)
OCULUS... Rift (virtual reality product owned by Facebook)
OCULUSDome opening
oculusdesign representing an eye, as on funerary pottery found in megalithic tombs of Europe
oculusa round window
oculuscircular opening, esp. one at the apex of a dome
oculuseye