We don't have synonyms for transfat yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are transfer, transmit and transit.
(n) :
Alternative spelling of trans fat. [(organic chemistry) An unsaturated fat with carbon-carbon double bonds in the trans configuration, especially one prepared by partial hydrogenation, associated with an elevated risk of coronary heart disease.]
(n) :
Alternative spelling of trans fat. [(organic chemistry) An unsaturated fat with carbon-carbon double bonds in the trans configuration, especially one prepared by partial hydrogenation, associated with an elevated risk of coronary heart disease.]