Question:
There is an error on your website. You call the 18th letter of the Hebrew alphabet "tzadik" but there is no "k" at the end of its name.
Answer:
You are correct that the proper name of the letter is "tzadi" and it has indeed been suggested calling the צ "tzadik" is a misnomer, which developed as result of the "tzadi" being followed by the "kuf"—kind of like the "elemeno," which many English-speaking tots think is one letter when they learn the ABCs.
However, it is not a simple error. There is a very old tradition of referring to the צ as a "tzadik," which means "righteous person" In fact Rabbi David ibn Zimra testified that the Torah teachers of his 15th century Spanish childhood would teach their charges to call the letter "tzadik."1
Now, the association of the צ and the tzadik go back even further. The schoolchildren in the days of Rabbi Joshua ben Levi would draw this connection and say that the bowed צ preceding the straight ץ teaches that the tzaddik who is bowed and humble in this world will stand tall and proud in the world to come.2 3
