[land.mark] n (bef. 12c) 1: an object (as a stone or tree) that marks the boundary of land
2. a: a conspicuous object on land that marks a locality b: an anatomical structure used as a point of orientation in locating other structures
3: an event or development that marks a turning point or a stage
4: a structure (as a building) of unusual historical and usu. aesthetic interest; esp: one that is officially designated and set aside for preservation