Recessions in developed economies are often defined as two consecutive quarters of declining GDP, and this was the first. Most economists do however think there will be further falls in output.

This was the first contraction in the British economy for sixteen years.

Andrew Walker, BBC News, London

is facing a recession
will probably enter a period when the economy is not doing well and conditions for business are bad

be revised
looked at again and, possibly, change

are consistent with
do not contradict, are logically linked to

assessment
conclusion, finding

defined
identified, classed, categorised

two consecutive quarters
two periods of three months that come one after the other

declining
falling, decreasing, diminishing, becoming smaller

GDP
short for gross domestic product, i.e. the total production of goods and services in a country

there will be further falls in output
the production of goods and services will continue to decline

contraction
when something (here, the economy) becomes smaller