post-exposure prophylaxis (treatment given very shortly after exposure to an infectious agent, such as rabies or the HIV virus, to prevent infection)

PEP must begin within 72 hours of exposure

(in the UK) a personal equity plan, a scheme allowing individuals to hold shares and unit trusts free of tax on dividends and capital gains (replaced in 1999 by the ISA)

energy and high spirits; liveliness

he was an enthusiastic player, full of pep

make someone or something more lively or interesting

measures to pep up the economy

(in the UK) an investment scheme whereby personal investors could invest a limited sum each year in shares or unit trusts in British companies without liability for tax on dividends or capital gains (closed to new subscriptions in 1999, when replaced by the ISA)