Stagflation is the combination of high inflation, stagnant economic growth, and elevated unemployment. The term stagflation, a portmanteau of "stagnation" and "inflation", was popularized, and probably coined, by British politician Iain Macleod in the 1960s, during a period of economic distress in the United Kingdom. It gained broader recognition in the 1970s after a series of global economic shocks, particularly the 1973 oil crisis, which disrupted supply chains and led to rising prices and slowing growth. Stagflation challenges traditional economic theories, which suggest that inflation and unemployment are inversely related, as depicted by the Phillips Curve.

Stagflation presents a policy dilemma, as measures to curb inflation—such as tightening monetary policy—can exacerbate unemployment, while policies aimed at reducing unemployment may fuel inflation. In economic theory, there are two main explanations for stagflation: supply shocks, such as a sharp increase in oil prices, and misguided government policies that hinder industrial output while expanding the money supply too rapidly. The stagflation of the 1970s led to a reevaluation of Keynesian economic policies and contributed to the rise of alternative economic theories, including monetarism and supply-side economics.

The term, a portmanteau of stagnation and inflation, is generally attributed to Iain Macleod, a British Conservative Party politician who became Chancellor of the Exchequer in 1970. Macleod used the word in a 1965 speech to Parliament during a period of simultaneously high inflation and unemployment in the United Kingdom. Warning the House of Commons of the gravity of the situation, he said:

We now have the worst of both worlds—not just inflation on the one side or stagnation on the other, but both of them together. We have a sort of "stagflation" situation. And history, in modern terms, is indeed being made.

Macleod used the term again on 7 July 1970, and the media began also to use it, for example in The Economist on 15 August 1970, and Newsweek on 19 March 1973. John Maynard Keynes did not use the term, but some of his work refers to the conditions that most would recognise as stagflation.

The United Kingdom experienced an outbreak of inflation in the 1960s and 1970s. As inflation rose, British policy makers failed to recognise the primary role of monetary policy in controlling inflation. They tried to use non-monetary policies and devices to respond to the economic crisis. Policy makers also made "inaccurate estimates of the degree of excess demand in the economy, [which] contributed significantly to the outbreak of inflation in the United Kingdom in the 1960s and 1970s."

Stagflation was not limited to the United Kingdom. Economists have shown that stagflation was prevalent among seven major market economies from 1973 to 1982. After inflation rates began to fall in 1982, economists' focus shifted from the causes of stagflation to the "determinants of productivity growth and the effects of real wages on the demand for labor".

Economists offer two principal explanations for why stagflation occurs. First, stagflation can result when the economy faces a supply shock, such as a rapid increase in the price of oil. An unfavourable situation like that tends to raise prices at the same time as it slows economic growth by making production more costly and less profitable.