Theresia

Theresia is a feminine given name with origins in the Greek language. It is generally accepted to be a derivative of the name Theresa, which itself comes from the Greek word "theros," meaning "summer" or "harvest." Another possible origin is the Greek island of Thera (Santorini).

The name Theresia is common in various European countries, particularly in German-speaking regions and parts of Eastern Europe. Its prevalence can be attributed, in part, to the veneration of Saint Teresa of Ávila (also known as Saint Teresa of Jesus), a prominent Spanish Carmelite nun, mystic, and writer of the Catholic Church. In some countries, Theresia is seen as a more traditional or classic variation of Theresa.

While not as widely used as its shorter form, Theresa, Theresia remains a recognized and distinct name with a long history. It carries similar connotations of warmth, abundance (linked to the "harvest" etymology), and strength, possibly derived from the association with Saint Teresa.