Olana, the magnificent home of landscape painter Frederic Church, sits atop a lofty hill near Hudson, N.Y. On a recent visit there, I encountered a sign describing efforts to preserve Olana's "viewshed."

Ah, I thought, a small shelter where aesthetes can contemplate the sublime vistas that inspired Church.

Well, not quite. Here "viewshed" refers, not to a shed, but to the entire landscape visible from Olana. Local authorities and owners of surrounding properties are being asked to limit the building of structures that might sully this natural panorama.

Why am I picturing one of Church's majestic Hudson Valley paintings with a cell phone tower on the horizon?

The word "viewshed" intrigues me because it implicitly compares a field of vision to a watershed, an area drained by a river or stream system. The eye takes in the entire scene, just as a river and its tributaries absorb all the precipitation that falls on that landscape. Whether "viewshed" will eventually be included in dictionaries remains to be "scene."

But "viewshed" also raises the confusing linguistic issues surrounding its parent word, "watershed." Is a "watershed," as I previously suggested, a river basin? Or is it the dividing line between two river basins?

Amazingly enough, it's both.

Unlike most English words, "watershed" did not slowly evolve through Latin or Old English. It suddenly burst into modern English, full grown, during the early 1800s as a literal translation of the German "wasserscheide" ("water divide").

And this was its first meaning in English — a line along a region's hilltops or mountaintops separating the waters flowing into different river basins. But by the 1830s, this meaning had expanded to denote the slope down which water flows from the divide and, by the 1870s, to denote the entire gathering ground of a water system.

Just as the word "frontier" initially meant a border between two countries but soon came to indicate the entire area near the border, so "watershed" evolved to mean the whole region on one side of the divide.

But when people today use "watershed" metaphorically to mean "turning point" or "crossroads," as in "the 2008 election will be a real watershed," they're thinking of the original meaning of "watershed" — a dividing line.

And those who smugly view this metaphoric use of "watershed" as a mistake "because watershed means a drainage area" should be taken, not to the woodshed, but to the "viewshed," a new word based on the definition of "watershed" they prefer.

Rob Kyff, a teacher and writer in West Hartford, Conn., invites your language sightings. Send your reports of misuse and abuse, as well as examples of good writing, via e-mail to [email protected] or by regular mail to Rob Kyff, Creators Syndicate, 5777 W. Century Blvd., Suite 700, Los Angeles, CA 90045. To find out more about Rob Kyff and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.