Upon its return from the Pacific coast in the spring of 1806, the expedition camped on the Clearwater River near present-day Kamiah (pronounced KAM-ee-eye) from May 14 until June 10, waiting for the snow to melt on the crest of the Bitterroot Mountains. The captains themselves didn't name their camp here, but historians have come to call it Camp Chopunnish, Long Camp, or Camp Kamiah.
"Chopunnish" (pronounced Chop-PUN-ish) was the name Lewis and Clark mistakenly understood these people called themselves. Actually, they called themselves Tsoop-nit-paloo, "people from the mountains." The sign-language gesture for the word, the index finger pointing upward, then horizontally in front of the face. It was later interpreted by French Canadians to mean "Nez Percé," or "pierced nose." The French pronunciation would be NAY pear-SAY, but the people themselves now say either NEZ-purse or nez-PURSE. Their neighbors variously called them "dark brown," "people under the tule," and "Khouse eaters."1
Like many common tribal names, this one was coined by outsiders, and based on observed traits or characteristics that were not necessarily correct. Consider the name Indian, which 15th-century European explorers, having mistaken the coast of South America for the coast of the Indies, imposed on the people they found there. Unfortunately, it still implies that all of those people represent a single culture.
The Nez Perce didn't usually pierce their noses, though "chopunnish" has been said to have come from a word in the Sahaptin language meaning "piercing people," although it most likely came from a sign-language gesture for "coming from the mountains," or "the walking-out people." Their name for themselves is Nee-me-poo, which means "the real people."
Not that there's anything wrong with pierced noses, or ears, or anything else, of course. In one culture or another, it's one of those fads that come and go from generation to generation.
1. Khouse, or cous, pronounced cowz, is Lomatium cous, a staple food of Rocky Mountain Indians.Further reading:
Alvin M. Josephy, Jr., The Nez Perce Indians and the Opening of the Northwest. Abridged edition; Lincoln: University of Nebraska Press, 1965.
Allen P. Slickpoo, Sr., Noon Nee-Me-Poo: We, The Nez Perces). Nez Perce Tribe of Idaho, 1973.