Donald Trump’s apocryphal invention, which dates back to the noughties, takes title in dictionary’s annual reckoning of the most-used new expressions

“Fake news” has acquired a certain legitimacy after being named word of the year by Collins, following what the dictionary called its “ubiquitous presence” over the last 12 months.

Collins Dictionary’s lexicographers, who monitor the 4.5bn-word Collins corpus, said that usage of the term had increased by 365% since 2016. The phrase, often capitalised, is frequently a feature of Donald Trump’s rhetoric; in the last few days alone he has tweeted of how “the Fake News is working overtime” in relation to the investigation into Russian interference in the 2016 US presidential elections, and of how “Fake News [is] weak!”

Trump has used the term frequently, and claimed last week to have invented it – “the media is really, the word, one of the greatest of all [the] terms I’ve come up with, is ‘fake’ … I guess other people have used it perhaps over the years, but I’ve never noticed it,” he told an interviewer. This etymology was disputed by the dictionary.

Collins said that “fake news” started being used in the noughties on US television to describe “false, often sensational, information disseminated under the guise of news reporting”. Its usage has climbed since 2015, according to the dictionary, and really took off this year, with its ubiquity to be acknowledged with a place in the next print edition of the Collins Dictionary.

A number of other words related to politics and current affairs were also in its list of the words of the year. “Echo chamber”, defined as “an environment, especially on a social media site, in which any statement of opinion is likely to be greeted with approval because it will only be read or heard by people who hold similar views”, has seen a “steady increase” in usage over the last five years , while “antifa” saw its usage rise by almost 7,000% following violent clashes between anti-fascist protesters and the far right, particularly in the US.

Corbynmania, up by 310%, was also on the list: Collins said the term for “fervent enthusiasm” for Jeremy Corbyn “first emerged in 2015 and after a dip last year made a striking comeback in 2017 as the Labour leader impressed on the campaign trail”.

“Much of this year’s list is definitely politically charged, but with a new president in the US and a snap election in the UK, it is perhaps no surprise that politics continues to electrify the language,” said Collins’s head of language content, Helen Newstead.

Quick guide Collins Dictionary words of the year 2017 Show Hide Fake news noun: false, often sensational, information disseminated under the guise of news reporting Antifa noun: (1) an antifascist organization (2) a member of an antifascist organization adjective: (3) involving, belonging to, or relating to an antifascist organization Corbynmania noun: fervent enthusiasm for Jeremy Corbyn, the leader of the UK Labour Party Cuffing season noun: the period of autumn and winter, when single people are considered likely to seek settled relationships rather than engage in casual affairs Echo chamber noun: an environment, especially on a social media site, in which any statement of opinion is likely to be greeted with approval because it will only be read or heard by people who hold similar views Fidget spinner noun: a small toy comprising two or three prongs arranged around a central bearing, designed to be spun by the fingers as means of improving concentration or relieving stress Gender-fluid adjective: not identifying exclusively with one gender rather than another Gig economy noun: an economy in which there are few permanent employees and most jobs are assigned to temporary or freelance workers Insta adjective: of or relating to the photo-sharing application Instagram Unicorn noun: (1) an imaginary creature depicted as a white horse with one long spiralled horn growing from its forehead, regarded as symbol of innocence and purity (2) a recently launched business enterprise that is valued at more than $1bn

“‘Fake news’, either as a statement of fact or as an accusation, has been inescapable this year, contributing to the undermining of society’s trust in news reporting: given the term’s ubiquity and its regular usage by President Trump, it is clear that Collins’s word of the year is very real news.”

Other words selected by Collins for its list of “new and notable words that reflect an ever-evolving language” include “gender-fluid”, defined as “not identifying exclusively with one gender rather than another”, which increased in use by 65% over the last year, “cuffing season”, defined as “the period of autumn and winter when single people are considered likely to seek settled relationships rather than engage in casual affairs”, and fidget spinner, the toy that is being twirled by children across the UK.

“Gig economy”, defined as “an economy in which there are few permanent employees and most jobs are assigned to temporary or freelance workers”, also makes the list, as does “Insta”, relating to social-media app Instagram.

The remaining new words and meanings will be added to CollinsDictionary.com, and considered for inclusion in future print editions of the dictionary.