Deliberately recorded backwards in a track that is meant to be played forwards.(adjective)
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Use "backmasked" in a sentence
"While shows like _Fringe_ can pack more into a single episode via backmasked audio, nonlinear time shifts, and external websites — though, to be fair, _How I Met Your Mother_, a half-hour sitcom, has also done all these things — shows like _The Wire_ and _Breaking Bad_ have been able to slow down their storytelling substantially with the knowledge that audiences will just “stack” a few episodes together and watch them in blocks."
"Then I would have my A&R man deny specifically the unmade allegations that there were hidden backmasked messages on the album this was back in the days of wax biscuits, honeychile."
"It illustrates backmasked subliminals sort of but I particularly liked how I couldn't understand the backwards lyrics until I read them, then I couldn't not understand them."