The Phoenician letter name ṭēth means "wheel", but the letter possibly (according to Brian Colless) continues a Middle Bronze Age glyph named ṭab "good", tayeb طيب in modern Arabic, based on the nfr "good" hieroglyph,
In gematria, Tet represents the number nine. When followed by an apostrophe, it means 9,000. The most common example of this usage is in the numbers of the Hebrew years (i.e. ט'תשנד in numbers would be the date 9754).
As well, in gematria, the number 15 is written with Tet and Vav, (9+6) to avoid the normal construction Yud and Hei (10+5) which spells a name of God. Similarly, 16 is written with Tet and Zayin (9+7) instead of Yud and Vav (10+6) to avoid spelling part of the Tetragrammaton.
Tet is also one of the seven letters which receive a special crown (called a tagin) when written in a Sefer Torah. See Shin, Ayin, Gimmel, Nun, Zayin, and Tzadi.
Arabic Ṭāʼ
The letter is named ṭāʼ; standard pronunciation: [tˤ]. It is written in several ways depending in its position in the word: