the position of a prominent or well-known object in a particular landscape
"the church steeple provided a convenient landmark"
an event marking a unique or important historical change of course or one on which important developments depend
"the agreement was a watershed in the history of both nations"
a mark showing the boundary of a piece of land
"The old stone pillar served as a landmark marking the northern boundary of the farm."
an anatomical structure used as a point of origin in locating other anatomical structures (as in surgery) or as point from which measurements can be taken
"The surgeon identified the radial artery as a crucial landmark to locate the nearby nerve during the procedure."
An object that marks the boundary of a piece of land (usually a stone, or a tree).
"The ancient oak tree served as a landmark marking the northern boundary of their farm."
In plain English: A landmark is a famous building, monument, or natural feature that people use to recognize their location.
"The old clock tower is a famous landmark in our city center."
Usage: As a noun, use "landmark" to refer either to a physical marker like a stone or tree that defines property boundaries or to a famous structure designated for historical significance. When using it as a verb, remember that the action requires an official government designation rather than just public recognition of importance.
To officially designate a site or building as a landmark.
"The city council voted to landmark the historic theater, ensuring its preservation for future generations."
In plain English: To landmark something is to mark it with signs so people can find their way there easily.
"The new bridge will landmark our city's skyline for generations to come."
The word landmark comes from Old English, where it originally meant a boundary. It entered modern usage as a combination of the words "land" and "mark."