calendar(n) a particular system for organizing the days of the year by month
sundial(v) a device that is used to show the time of day by the position of the sun,using a plate with markings like a clock and an object with a stright edge-- like a stick- that casts a shadow onto the plate
hourglass(n) a device for measuring time,usually with a thin stream of sand that falls between two chambers over the given time