urate calculus uric acid calculus. urethral calculus a urinary calculus in the urethra; symptoms vary according to the patient's sex and the site of lodgment. uric acid calculus a hard, yellow or reddish-yellow urinary calculus formed from uric acid.
In some traditions, the first day of Christmas begins on the evening of December 25th with the following day considered the First Day of Christmas (December 26th). In these traditions, the twelve days begin December 26 and include Epiphany on January 6. The origin and counting of the Twelve Days is complicated, and is related to differences in calendars, church traditions, and ways to observe this holy day in various cultures (see Christmas).
Many Orthodox churches recognize the holiday dates according to the Julian calendar. Christmas is still on December 25 in the Julian calendar so the January 7 date is only valid between 1901 and 2100 The Gregorian date for Orthodox Christmas will be January 8 in 2101 if the Julian calendar is still used.