The spelling of the word "firle" may seem unusual, but it follows the traditional English pronunciation rules. In IPA phonetic transcription, it is written as /fɜːl/. This means that the vowel sound is "er" as in "her", followed by the consonant sound "l". The "i" is silent and serves as a marker for the "long e" sound in the word. Despite its unusual spelling, "firle" is a valid and commonly used English word.