a. [f. as prec. + -AL.] Belonging to a set of fifty; containing fifty days.
1844. Lingard, Anglo-Sax. Ch. (1858), II. xi. 179, note. The quinquagesimal days were the fifty days between Easter and Whitsunday.
1884. Schaff, Encycl. Relig. Knowl., III. 1801/2. As designating the last day of this quinquagesimal period, the word ‘Pentecost’ is first found in … 305.
