Theta
Theta , noun
[Latin, from Greek qh^ta, the Greek letter θ, T.]
A letter of the Greek alphabet corresponding to th in English; -- sometimes called the unlucky letter, from being used by the judges on their ballots in passing condemnation on a prisoner, it being the first letter of the Greek qa`natos, death.
Collocations (1)
Theta function (Mathematics) , one of a group of functions used in developing the properties of elliptic functions.