Rom 1:7 To all that be in Rome, beloved of God, called to be saints: Grace to you and peace from God our Father, and the Lord Jesus Christ.
The word "saint" comes from the Latin "sanctus" (as an adjective, "holy," or a noun "holy person"). It's used in the Bible both of living persons and (biologically) dead ones -- one example of the latter usage being in the passion narrative in Matthew.
It goes without saying (I hope) that all Christians are "called to be saints" -- I'm talking about the kind in heaven. And of course, it is also true that all Christians are called to be "holy," and are alreadly "holy," at least in the sense of being set apart and dedicated to God.