NANO comes from the Greek nanos, meaning "dwarf." For a prefix meaning "small," English got by for centuries with the Greek micro-, and later mini- came to be used widely as well. But only recently, as a result of advances in scientific knowledge and technology, has there been a need for a prefix meaning "extremely small"--a need that's been filled by nano-, which today is being attached to all kinds of words, sometimes not very seriously (nanoskirt, nanobrained, etc.).

SUPER a Latin prefix meaning "over, higher, more than," has become one of the most familiar prefixes in English, one of those prefixes that we use to create new words all the time: supermodel, superpowerful, superjock, supersize, supersweet--the list goes on and on. This all seems to have started in 1903 when the playwright G.B.Shaw translated the German word ubermensch, Nietzsche's famous term for the person who rises to heroic heights through discipline and creative power, in the title of his play Man and Superman. The comic-book character with the same name wouldn't make his appearance for another 30 years.

DE in Latin means "down, away." So a descent is a downward slop or climb, and a decline is a downward slide (of health, income, etc.). To devalue something is to take value away from it. And you might describe a depressed friend as "down."

NUL/NULL comes from the Latin word nullus, "none," which is itself a combination of ne- ("not") and ullus ("any"). Have you ever noticed how many of our negative words start with n-? Think of no, not, never, nothing, none, no one, nowhere, and the hundreds of non- words--just about all of which go back to the same Greek root.

ARM comes from the Latin arma, meaning "weapons, tools." The root is seen in such English words as arms (i.e., weapons), armed, and army. It has nothing to do with the limb that starts at your shoulder; the name for that kind of arm comes from the Latin word meaning "shoulder."

SURG comes from the Latin verb surgere, meaning "to rise, spring up." Our noun surge means "a sudden, large increase," and the verb surge means "to move with a surge." A storm surge occurs when violent storm winds at sea cause the water to pile up higher than normal sea level. A surge protector keeps a spike in electrical current from "frying" your computer when a lightning strike sends a sudden surge down the wires.

STRAT comes from the Latin word stratum, meaning "spread" or "bed." Strata, a form of the same word, came to be used by the Romans to mean "paved road"--that is, street.

LATER comes from the Latin adjective lateralis, meaning "side." The noun for "side" in Latin was latus, and the same word served as an adjective meaning "wide." The releationship between the two isn't hard to spot, since something wide extends far out to its sides. So lines of latitude extend east-west around the earth, in the dimension we tend to think of as its width (unlike lines of longitude, which extend north-south, in the dimension that, for some reason, we decided to think of as its "length").

TOM comes from the Greek root meaning "cut." Thus, the Latin word anatomia, from which we get anatomy, means "dissection"--that is cutting or separating the parts of an organism for detailed examination. In a lobotomy, the nerves linking a brain lobe to the rest of the brain are removed; even though lobotomies have hardly been performed in the last 50 years, the idea can still fill us with horror.

IATR from the Greek iatros, "healer, physician," usually hides in the middle of words, where it isn't immediately noticed. A pediatrician treats children (see PED). A psychiatrist is a physician who treats mental problems. (A psychologist, by contrast, doesn't have a medical degree and thus can't prescribe drugs.) And a psysiatrist is a doctor who pratices "physical medicine and rehabilitation," which may involve such things as testing various physical abilities, relieving pain through electric heat or massage, or training patients to exercise or to use an artificial limb.