The nominal height of the surface of the oceans above which heights of geographical features and aircraft flight levels are measured.

Taking place or existing at a high level, altitude or elevation. / Of or pertaining to a person of a high social position or high rank within a hierarchy or organization. / Consisting of such people.

(chiefly Britain) An at-grade crossing between a railway line and an ordinary road, with rails and road at the same level.

relatively unimportant / not intense / (computing) of, or relating to a program, or to code in which each statement corresponds to a single machine instruction / detailed

Highest. / Best. / (Internet) Applied to domains at the highest level, such as .uk covering all sites for the United Kingdom.

(programming) read-eval-print loop

The depth of snow accumulated on the ground. / (meteorology, chiefly Western US) The altitude, in a mountainous region, above which precipitation falls as snow.

(idiomatic) Sensible; rational; possessing sound judgment.

(tool) A tool employing a chamber with a colored liquid (usually alcohol, hence spirit) and an air bubble, used to determine a horizontal or vertical reference line.

(rail transport) An at-grade junction between two crossing railroad tracks.