Acting in anticipation of future problems, needs, or changes.

People who tend to *react* to a problem only when it's gotten serious could be called *reactive* people. Until recently, *reactive* (in this sense) didn't really have an antonym. So *proactive* was coined to describe the kind of person who's always looking into the future in order to be prepared for anything. A good parent attempts to be proactive on behalf of his or her children, trying to imagine the problems they might be facing in a few months or years. A company's financial officers study the patterns of the company's earnings to make sure it won't risk running short of cash at any point in the next year or two. *Proactive* has only been around a few decades, and it can still sometimes sound like a fashionable buzzword.

Being, involved in, or doing professional work, and especially legal work, donated for the public good.

In Latin, *pro bono publico* means “for the public good”; in English we generally shorten the phrase to *pro bono*. Donating free legal help to those who need it has long been a practice of American law firms; the American Bar Association actually recommends that all lawyers donate 50 hours a year. Pro bono work is sometimes donated by nonlegal firms as well. For example, an advertising firm might produce a 60-second video for an environmental or educational organization, or a strategic-planning firm might prepare a start-up plan for a charity that funds shelters for battered women.

One who argues in favor of something: advocate.

*Proponent* comes from the same Latin word as *propose*, so a proponent is someone who proposes something, or at least supports it by speaking and writing in favor of it. Thus, for example, proponents of casinos argue that they create jobs, whereas proponents of a casino ban—that is, casino *opponents*—argue that they're corrupting and they take money away from people who can't afford it. As a rule, just about anything important that gets proposed also gets *opposed*.

Done or existing as something that is required but that has little true meaning or importance.

A lot of things are done for the sake of appearances. A teacher might get officially observed and evaluated every three years, even though everyone knows she's terrific and the whole thing is strictly pro forma. A critic might say that a orchestral conductor gave a pro forma performance, since his heart wasn't in it. A business owner might make a pro forma appearance at the funeral of a politician's mother, never having met her but maybe hoping for a favor from her son sometime in the future. In business, *pro forma* has some special meanings; a pro forma invoice, for example, will list all the items being sent but, unlike a true invoice, won't be an actual bill.

To jut out from the surrounding surface or context.

Since *trudere* means “to thrust” in Latin, *protrude* means basically “to thrust forward.” If your neighbors' patio protrudes over your property boundary, you may want to discuss it with them. A *protruding* disc in your spine may have to be operated on sooner or later; superficial *protrusions*, such as corns or bunions, tend to be less serious than more deeply rooted ones.

Measures designed to preserve health and prevent the spread of disease.

In Greek, *phylax* means “guard,” so *prophylactic* measures guard against disease by taking action ahead of time. Thus, for example, before the polio vaccine became available, prophylaxis against polio included avoiding crowds and public swimming pools. These days a well-known kind of *prophylactic* is used to prevent sexually transmitted diseases; but prophylactic measures only work when people use them.

(1) To proclaim or make public. (2) To put (a law) into effect.

All laws need to be made public in some way so that citizens may know if they're in danger of breaking them. Since they can't be expected to go into effect until the population knows they exist, *promulgate* has the two meanings “proclaim” and “put into effect.” In ancient Greece and Rome, when most people couldn't read, a new written law would actually be proclaimed in a public place; we've all seen such scenes in historical movies. But today *promulgation* of a law generally occurs simply by its being published in an official government publication and on a government Web site. New laws are also often reported in newspapers and on TV, though rarely in complete form.

(1) An introduction to a literary work. (2) An introductory event or development.

In ancient Greek drama, the *prologos* (a word that means basically “speaking before”) was the opening portion of the play, before the entry of the all- important chorus. It might be spoken by a single actor, maybe playing a god, who would “set the scene” for the audience. Playwrights today instead often provide the same kind of “scene-setting” information through dialogue near the play's beginning; in movies, it may appear (as in the “ Star Wars” series) in the form of actual written text. In a nonfiction book, the lead-in is now usually called a *preface* or *introduction*; novels rarely provide any introduction at all. Still, *prologue* remains a useful word for nonliterary purposes. The saying “The past is prologue” tells us that, in real life, almost everything can be a prologue to what follows it.