LONDON — Many of us have felt it, and now it’s official: “brain rot” is the Oxford dictionaries’ word of the year. Oxford University Press said Monday that the evocative phrase “gained new prominence in 2024,” with its frequency of use increasing 230% from the year before. Oxford defines brain rot as “the supposed deterioration of a person’s mental or intellectual state, especially viewed as the result of overconsumption of material (now particularly online content) considered to be trivial or unchallenging.” The word of the year is intended to be “a word or expression that reflects a defining theme from the past 12 months.” “Brain rot” was chosen by a combination of public vote and language analysis by Oxford lexicographers.