Many languages have words that show this phenomenon, and some use it as a regular part of their grammar, such as in Hebrew and the Fur language. The process of metathesis has altered the shape of many familiar words in the English language, as well.
The original form before metathesis may be deduced from older forms of words in the language's lexicon, or, if no forms are preserved, from phonological reconstruction. In some cases, including English "ask" (see below), it is not possible to settle with certainty on the original version.