Dam, Delta, Distributary: Origins, Forms, Histories of Words Meaning River, Lake

The natural features of a region are its topography (Greek topos, "place").

Freshwater bodies, such as rivers and lakes, are among the most important topographic features of a region. Many terms relating to freshwater features have little-known meanings and/or colorful etymologies.

In the current alphabetic series of such words, here are the origins, forms, and histories of dam, delta, and distributary. The dates of forms and meanings come from the Oxford English Dictionary and Merriam-Webster's Collegiate Dictionary.

Dam
Modern English dam comes from Middle English dam (14th century), probably from Middle Dutch dam(m) ("dam"). The word is akin to Old English fordemman ("to stop up"), Middle High German tam ("dam"), and Old High German temman ("to dam").

A body of water confined by a barrier is a dam (c. 1325).

The barrier built across a watercourse to confine water is also a dam (c. 1440).

Delta
Modern English delta comes from Middle English deltha (13th century), from Greek delta, of Semitic origin. The word is akin to Hebrew daleth ("daleth," the fourth letter of the Hebrew alphabet, from deleth, "door").

Delta is the name of the fourth letter of the Greek alphabet, which, in its capital form, is triangular in shape. The word in this sense entered English in the 13th century.

Any of various objects or features whose shape suggests the triangular Greek letter is also known as a delta.

Historically, the most famous example of such a use of the word is the Nile River delta (formerly usually capitalized, 1555) in Egypt, the triangular tract of alluvial land formed by the mouths of the two main branches of the Nile and the coast of the Mediterranean Sea. The Nile River delta is traditionally referred to as Lower Egypt, while the southern Nile valley, including the Valley of the Kings, is known as Upper Egypt.

Delta has also come to refer to any similar alluvial deposit at the mouth of any river (1790). Such a deposit commonly forms a nearly flat fan-shaped plain, sometimes covering a vast area, traversed by the various branches of the river as it distributes its water and its stream-borne sediments while heading downstream toward its mouth or mouths.

Distributary
Distributary entered English in the 19th century as a simple combination of the verb distribute and the suffix -ary ("place of").

A river branch flowing away from the main stream and not rejoining it is a distributary (1863). The branch "distributes" water from the main stream.

A distributary is contrasted with a tributary, a stream that flows into a larger body of water and "contributes" (or pays "tribute") to it.
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Encyclopaedia Britannica Ready Reference 2004. CD-ROM. Encyclopaedia Britannica, 2004.

Merriam-Webster's Collegiate Dictionary. 11th ed. Springfield, Mass.: Merriam-Webster, 2006.

Merriam-Webster's Geographical Dictionary. 3rd ed. Springfield, Mass.: Merriam-Webster, 2007.

The Oxford English Dictionary. 2nd ed. Oxford, England: Clarendon Press, 1989.