Tetrad (unit of area)

Tetrad (unit of area)

A tetrad is an area 2km x 2km square.

The term has a particular use in connection with the British Ordnance Survey national grid, and then refers to any of the 25 such squares which make up a standard hectad. These are numbered from A to Z according the "DINTY" system as shown in the grid below (taking its name from the second line).


Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Tetrad — may refer to:* Tetrad (chromosomal formation), a chromosomal formation in meiosis * Tetrad (general relativity), a mathematical frame of reference in general relativity * Tetrad (genetics), the four spores of a yeast * Tetrad (Greek philosophy),… …   Wikipedia

  • Area — This article is about the geometric quantity. For other uses, see Area (disambiguation). The combined area of these three shapes is between 15 and 16 squares. Area is a quantity that expresses the extent of a two dimensional surface or shape in… …   Wikipedia

  • Glossary of botanical terms — Many of the terms used in Wikipedia glossaries (often most) are already defined and explained within Wikipedia itself. However, lists like the following indicate where new articles need to be written and are also useful for looking up and… …   Wikipedia

  • plant — plantable, adj. plantless, adj. plantlike, adj. /plant, plahnt/, n. 1. any member of the kingdom Plantae, comprising multicellular organisms that typically produce their own food from inorganic matter by the process of photosynthesis and that… …   Universalium

  • angiosperm — /an jee euh sperrm /, n. Bot. a plant having its seeds enclosed in an ovary; a flowering plant. Cf. gymnosperm. [ANGIO + SPERM] * * * ▪ plant Introduction       any member of the more than 300,000 species of flowering plants (division Anthophyta) …   Universalium

  • Evolutionary history of plants — Plants have evolved through increasing levels of complexity, from the earliest algal mats, through bryophytes, lycopods, ferns and gymnosperms to the complex angiosperms of today. While the simple plants continue to thrive, especially in the… …   Wikipedia

  • List of genetic engineering topics — NOTOC # 3 end 5 end A Acentric chromosome Achondroplasia Active site Adam s Curse Adaptation Adenine Adenosine Adenosine diphosphate Adenovirus ADP Ala Alagille syndrome Albino Alcoholism Alkylating agent Allele Allele frequency Alleles… …   Wikipedia

  • literature — /lit euhr euh cheuhr, choor , li treuh /, n. 1. writings in which expression and form, in connection with ideas of permanent and universal interest, are characteristic or essential features, as poetry, novels, history, biography, and essays. 2.… …   Universalium

  • Media studies — is an academic discipline and field of study that deals with the content, history and effects of various media; in particular, the mass media . Media studies may draw on traditions from both the social sciences and the humanities, but mostly from …   Wikipedia

  • heredity — /heuh red i tee/, n., pl. heredities. Biol. 1. the transmission of genetic characters from parents to offspring: it is dependent upon the segregation and recombination of genes during meiosis and fertilization and results in the genesis of a new… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”