"Liberal" has come to have a lot of unpleasant connotations - for example, a "liberal" is seen as one who claims moral authority to apportion wealth to those he believes are more deserving than those who worked for, earned, or created that wealth; in many quarters, "liberal" is almost synonymous with "thief."
So the leftists are trying - hard - to use the term "progressive," safe in the knowledge that products of publik skool will not know the historic basis of the term "progressive" as applied to various marxist/fascist/totalitarian regiemes.
. . . but as times change so do the meanings of words. For example, the word "men" clearly means something now it didn't in better times for America.
Ditto for the word "gay."