Table 5.19 — ECs with labels beginning with O
Label Concept definition Figure(s) Code
OASIS A small, isolated, fertile, or green <TRACT> in a <DESERT_REGION> usually having a <WATERING_PLACE>; oasis.   817
OBJECT A person, place, thing, or concept; object.   818
OBJECT_PROPERTY_SET A <PROPERTY_SET> describing an <OBJECT>.   819
OBJECT_SET A <NON_EMPTY_SET> of <OBJECT>s.   820
OBSERVATION_STATION A station that is equipped for observation and study.   821
OBSERVATORY An <OBSERVATION_STATION> designed and equipped for making observations of astronomical, meteorological, or other natural phenomena; observatory [SOED, "observatory", 1].   822
OCCLUDED_FRONT A composite of two <ATMOSPHERIC_FRONT>s formed as a <COLD_FRONT> overtakes a <WARM_FRONT> or a <STATIONARY_FRONT>; occluded front.   823
OCCUPATION_ZONE A <REGION> temporarily held and controlled by a hostile military force; occupation zone.   824
OCEAN One of the major divisions of an expanse of salt <WATER> covering a <PLANETARY_SURFACE>; ocean.   825
OCEAN_BASIN A <TERRAIN_DEPRESSION> of an <OCEAN_FLOOR> approximately equidimensional in plan view and of variable extent; ocean basin.   826
OCEAN_FLOOR The <WATERBODY_FLOOR> of an <OCEAN>.   827
OCEAN_FLOOR_TOPOGRAPHIC-
_CONFIGURATION
A <WATERBODY_FLOOR_TOPOGRAPHIC_CONFIGURATION> of an <OCEAN_FLOOR>.   1440
OFF_ROUTE_BEARING The <DIRECTION> and distance from an <AID_TO_NAVIGATION> to a defined <WAYPOINT>; off route bearing.   828
OFFSHORE_LOADING_FACILITY A <FACILITY> located in a <WATERBODY> for loading and unloading <CARGO>; offshore loading facility.   829
OFFSHORE_PLATFORM A <STRUCTURE> placed in a <WATERBODY> and used: for production, loading, and discharge; as an <OBSERVATION_STATION>; or as a <SCIENCE_FACILITY>; offshore platform.   830
OIL_BARRIER A floating <BARRIER> to stop and contain oil flow on a <WATERBODY_SURFACE>; oil barrier.   831
OIL_DRILLING_RIG A <RIG> assembled primarily for the purpose of drilling an oil <WELL>; oil drilling rig.   832
OPEN_AIR_BATH An open air bath.   833
OPEN_WATER A <WATERBODY_REGION> where the <WATER> is flowing or free standing; open water.   834
OPERA_HOUSE A <BUILDING> that houses a <THEATRE> designed chiefly for the performance of operas; opera house.   835
ORCHARD A <TREED_TRACT> devoted to the cultivation of fruit or nut <TREE>s; orchard [AHD, "orchard", 1].   836
ORE_REFINERY An <INDUSTRIAL_WORKS> for purifying ores (for example: copper and/or silver) and extracting from them various metal and chemical products; ore refinery.   837
ORNAMENT A material <OBJECT> serving to adorn, beautify, or embellish; ornament [SOED, "ornament", 2.a]. An ornament is also known as a decoration.   1436
OUTBUILDING A small <BUILDING> that is separate from but is located near a main <BUILDING>; outbuilding.   838
OVERFALL_REGION A <WATERBODY_REGION> where short, breaking <WATER_WAVE>s are formed on the <WATERBODY_SURFACE> when a strong <WATER_CURRENT> passes over a <SHOAL> or other submarine obstruction or meets a contrary <WATER_CURRENT> or <WIND>; overfall region.   839
OVERHEAD_OBSTRUCTION An overhead obstruction (for example: an underpass, an overhead <PIPELINE>, and/or a <BUILDING_OVERHANG>) on a <TRANSPORTATION_ROUTE>.   840
OVERPASS A <BRIDGE> used to provide clearance to traffic on a <LAND_TRANSPORTATION_ROUTE> at a lower elevation; overpass.   841