1. Date in the Julian calendar, or actual number of the day within the year (i.e., July 17, 2006, is Julian date 2453934.1471). Astronomers and calendricists use the term in this sense, according to which a Julian date is a number, denoting a point in time, which consists of an integer part and a fractional part (e.g., 2439291.301), where the integer part is a Julian day number and the fractional part specifies the time elapsed since the start of the day denoted by that Julian day number. 2. In the commercial world the term “Julian date” has been used for a quite different concept, that of the number of the chronological date of the year 001 through 365 preceded by a two-digit year designation, so that January 1st = day 001 and February 28th = day 059; thus 06121 would be Monday, May 1, 2006. For the number of the day in the year, the proper term for this concept is “ordinal date.”