The spelling of the word "risibl" may seem unusual, but it can be explained through its phonetic transcription. The first syllable "ri" is pronounced as /rɪ/, which is pretty standard. The second syllable "si" is pronounced with a long "e" sound as /siː/. The final syllable "bl" is pronounced as a blend of /b/ and /l/, resulting in the sound /bl̩/. Therefore, the phonetic transcription of "risibl" is /ˈrɪ.siː.bl̩/. While uncommon, this spelling adheres to the rules of English phonetics.