Tessa is the short form of Theresa (also spelled Teresa) — itself of disputed etymology, possibly from the Greek therizein, meaning "to harvest," or from theros (summer), or even from the Greek island of Therasia. Some scholars derive it from the Greek tessares (four).
Tessa entered the U.S. top 1000 in 1981 and has been climbing steadily. Today it sits in the U.S. top 250. The actress Tessa Thompson, the heroine of Tess of the d'Urbervilles, and the protagonist Tessa in the After novels have kept the name in cultural view.
Tessa reduces to six — the number of warm focus.