CRYPTO comes from the Greek word for "hidden." To encrypt a message is to encode it--that is, to hide its meaning in code language. When a scientific term begins with crypto-, it always means that there's something hidden about it.

AB/ABS comes to us from Latin, and means "from," "away," or "off." Abuse is the use of something in the wrong way. To abduct is to "lead away from" or kidnap. Aberrant behavior that "wanders away from" what is acceptable. But there are so many words that include these root that it would be absurd to try to list them all here.

PED comes from the Greek word for "child." The same root also has the meaning "foot"(see PED), but in English words it usually isn't hard to tell the two apart.

TROP comes from the Greek tropos, meaning "turn" or "change." The troposphere is the level of the atmosphere where most weather changes--or "turns in the weather"--occur. And the Tropics of Cancer and Capricorn are the lines of latitude where the sun is directly overhead when it reaches its northernmost and southernmost points, on about June 22 and December 22 every year--that is, the point where it seems to turn and go back the other way.

NEO comes from the Greek neos, meaning "new." Neo- has become a part of many English words. Some are easy to understand; for example, neo-Nazi. Some are less so; you might not immediately guess that neotropical means "from the tropics of the New World," or that a neophyte is a "newcomer." When William Ramsay discovered four new gases, he named them al using Greek roots that at first glance might sound slightly mysterious: argon ("idle"), krypton ("hidden"), xenon ("strange")--and neon ("new").

NOV comes from the Latin word novus, meaning "new." To renovate an old house is to "make it new again"--that is, put it back in tip-top shape. The long-running PBS show Nova keeps its large audience up to date on what's new in the world of science. And when British king sent Scottish settlers to a large island off Canada's Atlantic coast in the 17th century, he named it Nova Scotia, or "New Scotland."

POS comes from the Latin verb ponere, meaning "to put" or "to place." You expose film by "placing it out" in the light. You compose a song by "putting together" a series of notes. And you oppose locating a new person prison in your town by "putting yourself against" it.

TEN from the Latin verb tenere, basically means "hold" or "hold on to." A tenant is the "holder" of an apartment, house, or land, but not necessarily the owner. A lieutenant governor may "hold the position" ("serve in lieu") of the governor when necessary.

MONO comes from the Greek monos, meaning "alone" or "single." So a monorail is a railroad that has only one rail; a monocle is an old-fashioned eyeglass that a gentleman used to squeeze into his eye socket; a monotonous voice seems to have only one tone; and a monopoly puts all ownership of a type of product or service in the hands of a single company.

UNI comes from the Latin word for "one." A uniform is a single design worn by everyone. A united group has one single opinion, or forms a single unit. A unitard is a one-piece combination leotard and tights, very good for skating, skiing, dancing--or riding a one-wheeled unicycle.