na-adjective, noun
fake; imitation; something made up
Refers to something fabricated or artificial, often with a negative connotation of being a sham or not genuine. Can be used as a noun or adjectival noun.
彼の話は全部こしらえものだった。
His story was all made up.
あの笑顔はこしらえものに違いない。
That smile must be fake.