Source : Webster's Revised Unabridged Dictionary (1913)

Calendar \Cal"en*dar\, v. t. [imp. & p. p. {Calendared}; p. pr.
   & vb. n. {Calendaring}.]
   To enter or write in a calendar; to register. --Waterhouse.

Calendar \Cal"en*dar\, n. [OE. kalender, calender, fr. L.
   kalendarium an interest or account book (cf. F. calendrier,
   OF. calendier) fr. L. calendue, kalendae, calends. See
   {Calends}.]
   1. An orderly arrangement of the division of time, adapted to
      the purposes of civil life, as years, months, weeks, and
      days; also, a register of the year with its divisions; an
      almanac.

   2. (Eccl.) A tabular statement of the dates of feasts,
      offices, saints' days, etc., esp. of those which are
      liable to change yearly according to the varying date of
      Easter.

   3. An orderly list or enumeration of persons, things, or
      events; a schedule; as, a calendar of state papers; a
      calendar of bills presented in a legislative assembly; a
      calendar of causes arranged for trial in court; a calendar
      of a college or an academy.

   Note: Shepherds of people had need know the calendars of
         tempests of state. --Bacon.

   {Calendar clock}, one that shows the days of the week and
      month.

   {Calendar month}. See under {Month}.

   {French Republican calendar}. See under {Vend['e]miaire}.

   {Gregorian calendar}, {Julian calendar}, {Perpetual
   calendar}. See under {Gregorian}, {Julian}, and {Perpetual}.

Source : WordNet®

calendar
     n 1: a system of timekeeping that defines the beginning and
          length and divisions of the year
     2: a list or register of events (appointments or social events
        or court cases etc); "I have you on my calendar for next
        Monday"
     3: a tabular array of the days (usually for one year)
     v : enter into a calendar