'Bench mark' definitions:

Definition of 'bench mark'

noun

A surveyor's mark on a permanent object of predetermined position and elevation used as a reference point [syn: benchmark, bench mark]

From: GCIDE

Bench \Bench\, n.; pl. Benches. [OE. bench, benk, AS. benc; akin to Sw. b[aum]nk, Dan b[ae]nk, Icel. bekkr, OS., D., & G. bank. Cf. Bank, Beach.]
1. A long seat, differing from a stool in its greater length. [1913 Webster]
Mossy benches supplied the place of chairs. --Sir W. Scott. [1913 Webster]
2. A long table at which mechanics and other work; as, a carpenter's bench. [1913 Webster]
3. The seat where judges sit in court. [1913 Webster]
To pluck down justice from your awful bench. --Shak. [1913 Webster]
4. The persons who sit as judges; the court; as, the opinion of the full bench. See King's Bench. [1913 Webster]
5. A collection or group of dogs exhibited to the public; -- so named because the animals are usually placed on benches or raised platforms. [1913 Webster]
6. A conformation like a bench; a long stretch of flat ground, or a kind of natural terrace, near a lake or river. [1913 Webster]
Bench mark (Leveling), one of a number of marks along a line of survey, affixed to permanent objects, to show where leveling staffs were placed. See bench mark in the vocabulary.
Bench of bishops, the whole body of English prelates assembled in council.
Bench plane, any plane used by carpenters and joiners for working a flat surface, as jack planes, long planes.
Bench show, an exhibition of dogs.
Bench table (Arch.), a projecting course at the base of a building, or round a pillar, sufficient to form a seat. [1913 Webster]

From: GCIDE

benchmark \benchmark\, bench mark \bench mark\ (Surveying)
1. Any permanent mark to which other levels may be referred. such as: (a) A horizontal mark at the water's edge with reference to which the height of tides and floods may be measured. (b) a surveyer's mark on a permanent object of predetermined position and elevation used as a reference point. [Webster 1913 Suppl. + WordNet 1.5]
2. something serving as a standard by which related items may be judged; as, his painting sets the benchmark of quality. [PJC + WordNet 1.5]
3. a test or series of tests designed to compare the qualities or performance of different devices of the same type. Certain sets of computer programs are much used as benchmarks for comparing the performance of different computers, especially by comparing the time it takes to complete a test. [PJC]