The spelling of the word "rebuck" may seem odd, but it can be explained with IPA phonetic transcription. The initial "r" is pronounced with a retroflex approximant, which is made by curling the tongue back to the roof of the mouth. The next sound is a "y" sound, made with the tongue in a high front position. Finally, the "buck" portion of the word is pronounced with a voiced velar stop (the "b" sound) and a back vowel (the "uh" sound). Together, these sounds create the unique spelling of "rebuck."