Note:  Do not rely on this information. It is very old.

T

T,the twentieth letter of our alphabet, is derived from the Greek tau, which was in all respects the equivalent to the Semitic letter of the same name. It is the hard or voiceless dental mute (whereas d is soft or voiced), and is produced by the contact of the tip of the tongue with the teeth (as in French), or the gum behind the teeth (as in English), or the tip of the tongue may be bent back against the palate, in which case the sound is called "cerebral."