A replica was an exact reproduction of someone or something.
A computer programmed and projected hologram of Losira appeared to the USS Enterprise landing party in 2269. She was the only representative left on the Kalandan outpost planet before the power to recreate them was destroyed. (TOS: "That Which Survives")
Later that year, when the Enterprise visited Gideon, he was transported to a replica of the Enterprise, designed, according to Spock, "to confuse his mind as to make him susceptible to some extraordinary experiment." (TOS: "The Mark of Gideon")