What’s now known as a “technical recession” has occurred if a country’s real GDP falls two quarters in a row. It was introduced in a 1974 NYT article by the then US Commissioner of Labor Statistics, Julius Shiskin.
The Office for Budget Responsibility (2023, p. 39) says that the UK “narrowly avoided a technical recession in the second half of 2022 as real GDP fell by 0.2 per cent in the third quarter, but was flat in the fourth quarter.”