Little Office of Blessed Virgin Mary
A form of prayer in honor of the Blessed Virgin, in structure resembling the Divine Office and consisting of the same elements, but in a shortened form.
In origin it is a monastic practise, generally attributed to Saint Peter Damian (11th century).
In the 12th century it became a supplement of the Roman Breviary and was frequently recited.
It was modified by Pius V in the 16th century and, instead of a supplementary office, became the office of the day for certain Saturdays, for those bound to the recitation of the Roman Breviary.
The Little Office, as distinct from the Office of the Blessed Virgin for Saturdays, is recited in choir by many religious communities of women, and as a private devotional practise, its use is widespread.
New Catholic Dictionary