Teresa is the Spanish, Italian and Portuguese form of Theresa, a name of uncertain origin that is usually linked to the Greek theros, "summer", or therizo, "to harvest", or to the island of Therasia. Saint Teresa of Avila, the great Spanish mystic, and Mother Teresa of Calcutta made it one of the most respected names in the Catholic world. Teresa ranked number 344 in 2000 and has declined steadily since, to number 668 in 2015 and number 911 in 2025.