The word "Trinity" does not occur in the Scriptures. The term combines the dual concepts of "three" and "unity," and thus it does convey a biblical idea, namely that the Godhead is composed of three distinct personalities that share one, identical essence, the nature of deity.
God is "one" as to essence (Deuteronomy 6:4; James 2:19), but the divine nature is possessed by Father, Son, and Holy Spirit (Matthew 28:19; 2 Corinthians 13:14). See GOD.