Verb - to relegate something, usually a project or work in progress, that is yet to be produced, to nonexistence and/or cancellation. Often refers to a person or team abandoning a project or promise of delivering a certain product or work.
Synonyms: Cancel, call off, abort, disestablish, terminate
Antonyms: Start, establish, uphold, ratify, support
"Hey, did that new game come out yet?"
"Nah, I heard it was slabbed until further notice. Sorry, bro
"Did you finish writing your memoir yet?"
"Nope, I slabbed it so I could write an erotic historical fiction novel instead."