adjective

made in exact imitation of something valuable with the intention to deceive or defraud.

counterfeit £10 notes

fake,faked,copied,forged,feigned,simulated,sham,spurious,bogus,imitation,substitute,dummy,ersatz,knock-off,pirate,pirated,phoney,pseud,pseudo,cod

noun

a fraudulent imitation of something else.

he knew the tapes to be counterfeits

fake,forgery,copy,reproduction,replica,imitation,likeness,lookalike,mock-up,dummy,substitute,fraud,sham,phoney,pirate,knock-off,rip-off,put-on,dupe

verb

imitate fraudulently.

my signature is extremely hard to counterfeit

fake,forge,copy,reproduce,replicate,imitate,simulate,feign,falsify,sham,pirate