I. ˈ ̷ ̷ˌ ̷ ̷ noun
1. : a mark for designating the boundary of land : a fixed object (as a monument of any sort, a river, marked tree, stone, ditch) by which the limits of a farm, a town, or other portion of territory may be known and preserved
2.
a. : a conspicuous object on land that serves as a guide to navigation at sea
b. : a natural object or man-made structure that marks a course or characterizes a locality
the Armory remains — a solid fortlike landmark of weathered brick — American Guide Series: Minnesota
a huge crooked tree was so prominent a landmark for early French voyageurs — American Guide Series: Michigan
c.
(1) : an anatomical structure used as a point of orientation in locating other structures (as in surgical procedures)
(2) anthropology : a point on the body or skeleton from which measurements are taken
3. : an event, achievement, characteristic, or modification that marks a turning point or a stage
forty years after its composition the essay stands as a landmark in American criticism — Lionel Trilling
a landmark in the shift of American values — W.H.Whyte
4. : a traditional guiding precept or principle
the young are abandoning old landmarks
II. noun
: a structure (as a building) of unusual historical and usually aesthetic interest ; especially : one that is officially designated and set aside for preservation