Having a pattern of small flowers and plants all over.

*Millefleur* came into French from the Latin *mille florae* (“a thousand flowers”), and from French directly into English. You may have seen the famed Unicorn Tapestries, in which the unicorn is seen frolicking, relaxing, being hunted, and being caught, all against a beautiful millefleur background. Italian has given us the similar word *millefiori*; though *fiori*, like *fleurs*, means “flowers,” *millefiori* actually refers to a type of multicolored ornamental glass. And the borrowed French word *mille-feuille* (*feuille* meaning “leaf”) is the name of a dish made with puff pastry, the kind of pastry whose flakes resemble thin dry leaves.

(1) Belief in the 1,000-year era of holiness foretold in the Book of Revelation. (2) Belief in an ideal society to come, especially one brought about by revolution.

Originally the *millennium* was not simply any thousand-year period, but instead the thousand years prophesied in the biblical Book of Revelation, when holiness will prevail on earth and Jesus Christ will preside over all. Later, *millennium* was extended to mean any period—always in the future— marked by universal happiness and human perfection. On several occasions over the centuries, members of Christian sects have become convinced that the biblical millennium was arriving and gathered together to await it. But nonreligious millenarians have also believed in a future society marked by human perfection. Even if they regard this future as certain, they've generally been willing to help it along by working for a political, social, or economic revolution. The millennium always seems to be approaching; to date, it hasn't arrived.

The earth is home to about 10,000 species of millipedes. Though they have no poison fangs, many of them can, when threatened, emit a liquid or gas poisonous to their enemies. If their structure were true to their name, millipedes would have a thousand legs, but in fact they have far fewer. Even so, a millipede in motion is a sight to ponder: How can it possibly coordinate all those legs so that it doesn't trip over itself? Like some tiny conga line or bunny hop, it scuttles away to a rhythm only it can hear.

One thousandth of a second.

A millisecond isn't long enough for the blink of an eye, but a few milliseconds may determine the winner of a swim race or a hundred-yard dash. With the ever-increasing speed of modern technology, even a millisecond has started to seem a little sluggish; computer operations are now measured in nanoseconds—that is, billionths of a second. ## HEMI/SEMI **HEMI/SEMI** means “half.” *Hemi-* comes from Greek, *semi-* from Latin. A *hemisphere* is half a sphere, and a *semicircle* is half a circle. (The French prefix *demi-*, which probably developed from Latin as well, also means “half”—as in *demitasse*, a little after-dinner coffee cup half the size of a regular cup.)

The tone at a half step.

A semitone (sometimes called a *half tone* or a *half step*) is the distance from a white key to a neighboring black key on the piano keyboard—for example, from G to G-sharp or from E to E-flat. In an octave (from G to the next G above, for instance), there are twelve semitones. Semitones are the smallest intervals that are used intentionally in almost any of the music you'll normally hear. Two semitones equal a *whole tone*—the distance from G up to A or from E down to D, for example.

The punctuation mark ; , used chiefly to separate major sentence elements such as independent clauses.

The semicolon was introduced into modern type by an Italian printer around 1566. But since it's actually the same symbol as the ancient Greek question mark, it's older than the colon (:), which first appears around 1450. Don't mix the two up. A colon introduces something: usually a list, sometimes a statement. A semicolon separates two independent but related clauses; it may also replace the comma to separate items in a complicated list.

*Hemi-*, unlike *semi*, almost always appears in scientific or technical words, including medical terms such as this one. A *hemiplegic*, like a paraplegic (who has lost the use of both legs), has usually suffered brain damage, often from a wound or blood clot. Other conditions that affect one side of the body are *hemihypertrophy* (excessive growth on one side), *hemiatrophy* (wasting on one side), and *hemiparesis* (weakness or partial paralysis).

A solid that conducts electricity like a metal at high temperatures and insulates like a nonmetal at low temperatures.

A semiconductor is a crystal material whose ability to conduct electricity rises as its temperature goes up. That is, it sometimes acts as a conductor and sometimes as an insulator. Its conducting ability can be much increased by chemical treatment. A manufactured chip of silicon, less than half an inch square, may contain millions of microscopic transistors, which can serve control and memory functions when installed in a computer, automobile, cell phone, DVD player, or microwave oven. ```