This is one of the three ancient methods, the other two are gematria and Netrikon, used by the Kabbalists to rearrange words and sentences in the Bible to derive the esoteric substratum and deeper spiritual meaning of the words.
Temurah has a second meaning also when pertaining to Judaism, particularly Hebrew mysticism, which is in association with the art of word-changing. This entails the changing of letters in certain words to create a new meaning for a Biblical statement. A.G.H.
Source: 2, 300.