Theta
Pronunciation : The"ta
Part of Speech : n.
Etymology : [L., fr. Gr. qha, the Greek letter th,
Definition : Defn: 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. Theta function (Math.), one of a group of functions used in developing the properties of elliptic functions.
Source : Webster's Unabridged Dictionary, 1913