MST
MST has 2 meanings
Must see today
A quick way of saying, "You've gotta see this today," as with something that can't wait until tomorrow; sometimes used to refer to movies or items for sale in classifieds or advertisements.
Example
The film critics reviews say it's a MST movie.
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A time keeping acronym that refers to the Mountain time zone in the U.S. during fall and winter; mostly made up of the Rocky Mountains; ahead of the Pacific Time Zone by 1 hour, behind the Central Time Zone by 1 hour, and behind the Eastern Time Zone by 2 hours.