noun
Etymology: translation of Medieval Latin immaculata conceptio
1. usually capitalized I&C : a conception in which the offspring is immediately and constantly preserved free from original sin by divine grace — used of the conception of the Virgin Mary in the womb of Saint Anne and made an article of faith of the Roman Catholic Church by Pius IX; distinguished from virgin birth
2. : conception not preceded by sexual intercourse ; broadly : production of something without evident source or origin
the naturalist must insist that reason is not of immaculate conception — H.J.Muller