mean sea level

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Related to sea-level datum: Geodetic datum

mean sea level

n.
The average level of the ocean's surface, calculated as the arithmetical mean of hourly tide levels taken over an extended period and used as the standard for determining terrestrial and atmospheric elevations and ocean depths.

mean sea level

n
(Surveying) (in the UK) the sea level used by the Ordnance Survey as a datum level, determined at Newlyn in Cornwall. See sea level

mean sea level

The average height of the surface of the sea for all stages of the tide; used as a reference for elevations. Also called MSL.