Diminutive of Theresa, possibly from Greek 'therizein' meaning to harvest or from the island Thera.
Tessie is the warmhearted diminutive of Theresa, a name whose etymology remains genuinely contested — scholars have proposed derivations from the Greek island of Thera, from therizo meaning "to harvest," and from the Greek therasia meaning "to carry." Whatever its root, the name was catapulted to prominence by two saints: Teresa of Ávila, the sixteenth-century Spanish mystic and reformer whose writings on prayer and contemplative life remain among the most extraordinary in Western Christianity, and Thérèse of Lisieux, the nineteenth-century French Carmelite whose "little way" of spiritual simplicity made her one of the most beloved saints of the modern era. Tessie carries their legacy at a friendlier, more approachable distance.
In America, Tessie became particularly beloved in the early twentieth century, and it achieved genuine pop-culture immortality in 1902 when the song "Tessie" — written by Will R. Anderson — became the anthem of the Boston Americans (later the Red Sox), sung by the Royal Rooters fan club at Huntington Avenue Grounds. The song reportedly unnerved the Pittsburgh Pirates during the 1903 World Series.
A century later, the Dropkick Murphys revived it before the Red Sox's 2004 championship run, and it has retained its place in Boston baseball folklore ever since. Shirley Jackson's haunting 1948 short story "The Lottery" centers on Tessie Hutchinson, a character whose breezy, complaining ordinariness makes the story's ending all the more devastating — a very different kind of cultural legacy. Today Tessie rides the broader wave of affectionate, slightly old-fashioned nicknames worn as given names. It is impossible to say without smiling.