| a theoretical line following approximately the 180th meridian, the regions to the east of which are counted as being one day earlier in their calendar dates than the regions to the west. |
International Date Line  (click for larger image in new window) n. An imaginary line through the Pacific Ocean roughly corresponding to 180° longitude, to the east of which, by international agreement, the calendar date is one day earlier than to the west. |
International Date Line  (ĭn'tər-nāsh'ə-nəl) Pronunciation Key
(click for larger image in new window) An imaginary line on the Earth's surface that is internationally agreed upon as the place where each new calendar day begins. The line extends from the North to the South Pole through the Pacific Ocean, roughly along the 180th meridian. The calendar day to the east of the line is one day earlier than it is to the west of the line. The International Date Line was established at the International Meridian Conference in 1884 in order to standardize time, especially for the purpose of travel. |