Merriam-Webster's Word of the Day for March 24, 2012 is:

demarcate • \dih-MAHR-kayt\  • verb
1 : to fix or define the limits of : delimit 2 : to set apart : distinguish

Examples:
A crumbling stone wall demarcated the property.

"The war on terrorism has made it hard to demarcate the proper lines between military action and law enforcement, simply because it doesn't resemble traditional wars between national armies." — From an article in the Chicago Tribune, January 3, 2012

Did you know?
"Demarcate" is set apart by its unique history. Scholars think it may have descended from the Italian verb "marcare" ("to mark"), which is itself of Germanic origin (the Old High German word for boundary, "marha," is a relative). "Marcare" is the probable source of the Spanish "marcar" (also "to mark"), from which comes the Spanish "demarcar" ("to fix the boundary of"). In 1493, a Spanish noun, "demarcación," was used to name the new meridian dividing the New World territory between Spain and Portugal. Later (about 1730), English speakers began calling this boundary the "line of demarcation," and eventually we began applying that phrase to other dividing lines as well. "Demarcation" in turn gave rise to "demarcate" in the early 19th century.

Merriam-Webster's Word of the Day for March 23, 2012 is:

pippin • \PIP-in\  • noun
1 : a crisp tart apple having usually yellow or greenish-yellow skin strongly flushed with red and used especially for cooking 2 : a highly admired or very admirable person or thing

Examples:
The CEO's retirement speech was a pippin.

"[Judge Len Goodman of 'Dancing with the Stars'] said … that the dance was 'first class.... It was crisp, it was sharp, it was like a pippin.'" — From an article by Allyssa Lee in the Los Angeles Times, September 27, 2011

Did you know?
Since the late Middle Ages, English speakers have experimented with the use of the word "pippin," which germinated from the Anglo-French word "pepin," meaning "seed" or "pip of a fruit." "Pippin" has been used to refer to a part of a pea embryo, a grain of gold, and a grape, but those uses were not hardy enough to become firmly rooted in the English language. The word did take root, however, in the soil of the northern regions of England, where it is used to describe a small fruit seed. In addition, it has widespread use as the name of a crisp, tart apple and of a person who is unique, usually in a pleasant way.