I don't know but looking at it I would assume it is a female form of
Dennis. A medieval form of
Dennis is Tenney, check
Tennyson.
"You sought a flower and found a fruit. You sought a spring and found a sea. You sought a woman and found a soul. You are disappointed."
"It does not become me to make myself smaller than I am." (
Edith Södergran 1891-1923)