THERA Meaning of THERA in English /thear"euh/ , n.a Greek island in the S Aegean, in the Cyclades group. 30 sq. mi. (78 sq. km). Also, Thira . Also called Santorin, Santorini . Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012