The materializer was technology associated with the transporter.

In 2265, Montgomery Scott made sure that the materializer was ready in the transporter room before he beamed the SS Valiant disaster recorder on board the USS Enterprise using the transporter. (TOS: "Where No Man Has Gone Before")

After this one use very early on in the series, the term has not been used again in the series. The term "materialized" is however often used to indicate that someone or something has appeared to it's destination after a transport.
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