TOP comes from topos, the Greek word for "place." A topic is a subject rather than a place; to the Greeks, the original word meant more or less "aout one place or subject (rather than another)"--which just goes to show that it's not always easy to trace a word's meaning from its root.

CENTR/CENTER comes from the Greek kentron and the Latin centrum, meaning "sharp point" or "center point of a circle." A centrifuge is a spinning machine that throws things outward from the center; the apparent force that pushes them outward is called centrifugal force.

DOM comes from the Latin domus, "house," and dominus, "master," and the two are indeed related. In the Bible, King Ahasuerus, angered by his queen's disobedience, proclaims that "every man is to be master of his own house," and in the Roman empire no one doubted that this was how it was meant to be. A domain is the area where a person has authority or is dominant--but we no longer think of a house as the domain of a single dominant memeber of a family.

OMNI comes from the Latin word omnis, meaning "all." In English words, omni- can mean "in all way," "in all place," or "without limits." An omnidirectional antenna, for example, is one that receives or sends radio waves equally well in all directions. And Omni by itself has been used repeatedly as a brand name for things as different as a hotel chain and a science magazine.

HOL/HOLO meaning "whole," comes from the Greek word holos, with the same meaning. The root can be found in catholic. When capitalized, Catholic refers to the worldwide Christian church based in Rome, which was once the "whole"--that is, the only--Christian church. Without the capital letter, catholic means simply "universal" or, when describing a person, "broad in one's interests or tastes."

RETRO means "back," "backward," or "behind" in Latin. Retro in English is generally a prefix, but has also become a word in its own right, usually used to describe old styles or fashions.

TEMPOR comes from the Latin tempus, meaning "time." A temporary repair is meant to last only a short time. The tempo, or speed, of a country-and-western ballad is usually different from that of a hip-hop number. The Latin phrase Tempus fugit means "Time flies," an observation that seems more true during summer vacation than in the dead of winter.

CHRON comes from the Greek word for "time." A chronicle records the events of a particular time, which is why so many newspapers have the name Chronicle. A chronometer is a device for measuring time, usually one that's more accurate (and more expensive) than an ordinary watch or clock.

TRI means "three," whether derived from Greek or Latin. A tricycle has three wheels. A triangle has three sides and three angles. And a triumvirate is a board or government of three people.

TRI means "three," whether derived from Greek or Latin. A tricycle has three wheels. A triangle has three sides and three angles. And a triumvirate is a board or government of three people.