'A situation in which urgent action is required to reduce or halt climate change and avoid potentially irreversible environmental damage resulting from it.'
'Climate emergency' has been named as the Oxford Word of the Year for 2019.
The word was chosen from an all-environmental shortlist that also included 'climate action', 'climate crisis', 'climate denial', 'eco-anxiety', 'ecocide', 'extinction', 'flight shame', 'global heating', 'net-zero' and 'plant-based'.
In a statement, Oxford University Press said the 'Word of the Year' is a word or expression shown through usage evidence to reflect the ethos, mood, or preoccupations of the passing year.
"Heightened public awareness of climate science ... has generated enormous discussion of what the UN Secretary-General has called 'the defining issue of our time'," the statement said.
Usage of the phrase 'climate emergency' increased steeply over the course of the year and by September it was more than 100 times as common as it had been the previous year.
Casper Grathwohl, President of Oxford Dictionaries, said "this has been a fascinating year for the word "climate", and we see that reflected especially in the way that English-speakers have combined it with other words."
In recent years the Oxford Word of the Year has been bestowed on words such as 'toxic', 'youthquake' and 'post-truth'.
Earlier this month, the rival Collins Dictionary named "climate strike" as its Word of the Year.