The Nuttall Encyclopedia
The doctrine held by the Roman Catholic Church that the Virgin Mary was conceived and born without taint of sin; first distinctly propounded in the 12th century, at which time a festival was introduced in celebration of it, and which became matter of dispute in the 14th century, and it was only in 1854 that it became by a bull an article of the Catholic faith.
Wood, James, ed. Entry for 'Immaculate Conception'. The Nuttall Encyclopedia. https://www.studylight.org/encyclopedias/eng/nut/i/immaculate-conception.html. Frederick Warne & Co Ltd. London. 1900.