Orthodox simply means classical Christianity. It is the original Christianity. The word “orthodox” means true, or undeviating, both in worship and teaching. It is not the name of a denomination. It is the Church you can read about in the New Testament, although it predates the New Testament, having its source in Christ Himself and the Apostles.

Orthodoxy exists in different lands and cities today, as in New Testament times, teaching the same one Lord, one Faith, and one Baptism, and making available to all men salvation and eternal life in our Lord, God and Savior Jesus Christ.

I would rather just say Christian, and often do, but sadly the qualifier Orthodox is necessary.