Arm, Catchment, Channel: 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 words relating to freshwater features have little-known meanings and/or colorful etymologies.

In the current alphabetic series of such terms, here are the origins, forms, and histories of arm, catchment, and channel. The dates of forms and meanings come from the Oxford English Dictionary and Merriam-Webster's Collegiate Dictionary.

Arm
Modern English arm goes back to Old English arm and earm (both before 12th century). The word is akin to Old High German aram ("arm"), Old Norse armr ("arm"), Latin armus ("shoulder"), Sanskrit irma ("arm"), and Greek arariskein ("to fit"). The basic meaning behind all these words is joining or fitting.

The original meaning of arm is the upper limb of the human body (before 12th century). The use of the word in extended senses to name any of various things that resemble a human arm also goes back to the Old English period (before 12th century).

One of the earliest such uses was to denote an inlet of water from a sea. Later water-related extensions of the word arm include an inlet from any other body of water; a long, narrow bay in the shoreline of a body of water; and a tributary or branch of a river or stream.

Catchment
Catchment entered the English language in the 19th century as a simple combination of the verb catch and the suffix -ment (indicating the concrete means of an action).

The word catchment (1847) is used in two senses: that part of a lake or river basin that collects rainfall and drains it into the lake or river, and the amount of water itself that is caught by the basin.

Channel
Modern English channel (16th century) comes from Middle English chanel (13th century), from Middle French chanel, from Latin canalis ("pipe, channel"), from canna ("reed"), from Greek kanna ("reed"), of Semitic origin. The word is akin to Arabic qanah and Hebrew qaneh, both meaning "hollow stick, reed."

The original meaning of channel is the hollow bed where a natural stream of water runs (13th century).

The word has developed many extended senses pertaining to anything resembling a streambed, such as an artificial watercourse (15th century).

Channel has also been used to denote water itself in various forms in the natural world. From the 15th to the 18th centuries, one meaning of the word, now obsolete, was a small stream or rivulet.

Since at least the 16th century, channel has acquired other water senses, including a relatively narrow piece of water connecting two larger bodies of water, either freshwater or saltwater (as in the English Channel); a navigable passage between shallows, as in an estuary; and the deeper part of a moving body of water, such as a river or a stream, where the main current flows or which offers the best passage.
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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.