According to Collins, the word "encapsulates the shared experience of billions of people" across the world.
From just 4,000 last year, “lockdown” became so popular that lexicographers registered an astronomical jump to more than 250,000 usages during 2020.
"Furlough", "key worker", "self-isolate" and "social distancing" as well as "coronavirus" were other pandemic-linked terms on the 10-strong list compiled by Collins.
It defines lockdown as "the imposition of stringent restrictions on travel, social interaction, and access to public spaces".
The word gained global popularity as governments around the world responded to the spread of Covid-19 in early 2020 which compelled countries to introduce strict restrictions on movement to break the chains of its transmission.
Aside from lockdown and other pandemic-linked words that got recognition by Collins, some non-virus-related words also made it. They are related to the social and political disturbances that characterised the year 2020.
The abbreviation "BLM", for the Black Lives Matter movement and its protest activities in the US and beyond to express displeasure at the death of the unarmed black man George Floyd who was molested by police officers.
According to Collins, "BLM" saw a 581% increase in usage.
Another word that made the list is "Megxit". The term was coined from Britain’s exit from the European Union simply known as Brexit, to describe the withdrawal of the Duke and Duchess of Sussex from royal duties.
"TikToker" also found a space in the list thanks to social media. It describes someone who shares content on the platform TikTok.
The last word of the list is "mukbang" - a term originating in South Korea which describes a host who broadcasts videos of themselves eating large quantities of food.
Speaking about the list, Helen Newstead, a language content consultant at Collins, said: "Language is a reflection of the world around us and 2020 has been dominated by the global pandemic.
"Lockdown has affected the way we work, study, shop, and socialize.
"With many countries entering a second lockdown, it is not a word of the year to celebrate but it is, perhaps, one that sums up the year for most of the world."
In 2019, Collins word of the year was "climate strike". It was the year in which 17-year-old Greta Thunberg led a global environmental movement.
Below are previous Collins words of the year:
2019: Climate strike
2017: Fake news
The Oxford English Dictionary also chose "climate emergency" as the word of the year 2019, "toxic" in 2018, "youthquake" in 2017 and "post-truth" in 2016.