Someone on Twitter who thinks they are famous but in reality nobody has heard of (usually a B-list celebrity or a journalist who writes for a little-known leftist publication). The main factor which separates them from the verified accounts belonging to real celebrities is that the Blue Checkmarks lack the self-awareness to realize that nobody really cares about their opinions, yet they act as though they are God's gift to political discourse as they spout their self-righteous hot takes on Twitter.

Abbreviation for:

I DON’T GIVE A FUCK WHAT THE CDC SAYS YOU BE WEARING YOUR MASK

a term describing someone who is verified on Twitter, giving them a blue checkmark, hence the name.
the term is a pejorative, predominantly used by right-wing people to describe left-wing journalists who tweet things that either are stupid or exactly what they expected from a person with the checkmark. usually both

A slur against "verified" Twitter users, who have a blue checkmark by their names. It's usually used to refer to journalists and prominent political figures.

Twitter's icon on the user profile page verifying that a high profile user name actually belongs to named user.

A neo-nazi/alt-right hate symbol, used to show approval of something.