The letter Tet is the ninth letter in the Hebrew alphabet, and also appears in various forms in a number of other Semitic language’s alphabets. As its name indicates, Tet has the sound of a “t”. Some believe that the meaning of the letter Tet is related to a Phoenician letter by the same name whose meaning was “wheel”. Nonetheless, in the Hebrew language, the letter itself, as well as its meaning is generally accepted to be connected to the Hebrew word “tov” (טוב), meaning “good”. While Tet is actually the least common letter in the Hebrew Bible, the first time it appears it is in the word “tov” which is used numerous times during the story of Creation.
As seen by its meaning and its usage in the Hebrew Bible, the Hebrew letter Tet has positive connotations of goodness. Nonetheless, as with many things in the spiritual realm, there is also a certain duality associated with this Hebrew letter. Thus, while it is the first letter in the Hebrew word for “purity” (טהרה), it is also the first letter in the Hebrew word for “impurity” (טומאה). Additionally, while it is the first letter in the word for good (טוב) which is used to describe G-d’s reaction to the creation of light, He then goes on to separate between the light and the darkness, thus connecting once again back to duality.
The Hebrew letter Tet has an interesting numerical value, as well. Due to the fact that Tet is the ninth letter in the Hebrew alphabet, it has the numerical value of nine. Nonetheless, when an apostrophe is added after the letter, it gives a value of 9000. Tet is used in another way numerically, as well. Due to the fact that according to Jewish law, some of the names for G-d are not to be pronounced, the Tet is used for the numbers 15 and 16 instead of what would be the expected construction of those numbers. The number 15, for example, should, in following the general pattern, be composed of the letter י, which has a value of 10 and the letter ה, which has a value of 5. These two letters together form one of the names of G-d which it is forbidden to use, however, and therefore ט, which has a value of 9 and ו, which has a value of 6 is the combination used for the Hebrew numerical representation of 15 (טו). This is how we get the name of the holiday Tu B’shvat, which is the 15th day of the month of Shvat!