noun

a thing that is not genuine; a forgery or sham.

fakes of Old Masters

forgery,counterfeit,copy,sham,fraud,hoax,imitation,mock-up,dummy,reproduction,lookalike,likeness,phoney,pirate,knock-off,rip-off,dupe

verb

forge or counterfeit (something).

she faked her spouse’s signature

forge,counterfeit,falsify,sham,feign,mock up,copy,reproduce,replicate,doctor,alter,tamper with,tinker with,pirate,fiddle (with)