why is thomas in the bible called the twin
Thomas the Apostle The name Thomas (Koine Greek: Θωμᾶς) given for the apostle in the New Testament is derived from the Aramaic or Classical Syriac: ܬܐܘܡܐ‎ Toma, equivalently from Hebrew Teom, meaning "twin". The equivalent term for twin in Greek, which is also used in the New Testament, is Δίδυμος Didymos.
Trinity The word "trinity" is derived from Latin trinitas, meaning "the number three, a triad". This abstract noun is formed from the adjective trinus (three each, threefold, triple),[21] as the word unitas is the abstract noun formed from unus (one).