physician's assistant: see physician assistant.

physician assistant (PA), health-care professional who provides patient services ranging from taking medical histories and doing physical examinations to performing minor surgical procedures; often called physician's assistant. Physician assistants work under the supervision of a physician, who can be on or off site. PAs receive two years of postgraduate training and pass a national certifying exam. They are licensed by the states. PAs, who typically deliver quality routine health care less expensively than doctors, are an increasingly important part of the American health-care system, as they are in Canada and some European countries.

personal digital assistant (PDA), lightweight, hand-held computer designed for use as a personal organizer with communications capabilities; also called a handheld. A typical PDA has no keyboard, relying instead on special hardware and pen-based computer software to enable the recognition of handwritten input, which is entered on the surface of a liquid crystal display screen. In addition to including such applications as a word processor, spreadsheet, calendar, and address book, PDAs are used as notepads, appointment schedulers, and wireless communicators for sending and receiving data, faxes, and electronic-mail messages. Introduced in 1993, PDAs achieved only modest acceptance during the remainder of the decade due to their relatively high price and limited applications, but improved software and lower prices subsequently led to more widespread use. See also palmtop.